Article

Resistance of long-lived lymphocytes and plasma cells in rat lymph nodes to treatment with prednisone, cyclophosphamide, 6-mercaptopurine, and actinomycin D

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

The cells of the popliteal lymph nodes of rats were labeled for 4 days after a secondary immunological stimulus. 31 days after the last dose of tritiated thymidine, groups of rats were started on courses of daily, intraperitoneal injections of prednisone, cyclophosphamide, 6-mercaptopurine, or actinomycin D. The initially low doses of these agents were doubled in successive weeks until either lymphoid hypoplasia or death occurred. Rats from each group were killed weekly, and the percentages of persisting, labeled small lymphocytes in the popliteal nodes were determined. Sections of these nodes were examined for persisting, labeled plasma cells. The per cent of lymphocytes labeled increased while the total number of lymphocytes decreased during treatment with prednisone and cyclophosphamide. Prednisone decreased the numbers of long-lived plasma cells, but these cells were preferentially resistant to cyclophosphamide. Neither 6-mercaptopurine nor actinomycin D had an appreciable effect on lymphoid tissues histologically nor on the proportions of labeled, long-lived lymphocytes and plasma cells before causing the deaths of the rats receiving them. These results indicate that long-lived lymphocytes and plasma cells survive treatment with the immunolytic drugs studied, and that long-lived lymphocytes are specifically resistant to prednisone and cyclophosphamide. We believe these results have an application to the attempts to find drugs useful in the treatment of immunologic rejections of organ transplants, and for therapy of autoimmune diseases.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... As a result of its action on the bone marrow, one would expect a decrease in the blood levels not only of polymorphonuclear leukocytes but also of monocytes and medium to large lymphocytes, since these cell types are known to be rapidly labeled in the bone marrow and blood following a single injection of aH-Tdr in vivo (11,13,22). Latta and Gentry (23) have, in fact, observed marked decreases in the counts of large lymphocytes and monocytes in mice treated with 6-MP, and Miller and Cole (24,25) have found that the only resistant ceils in lymph nodes of rats treated for long periods of time with 6-MP and other anti-proliferative agents were small lymphocytes and plasma cells. ...
... This observation raised the possibility that the clinical improvement observed in these patients resulted from an anti-inflammatory effect. The manifestation by thiopurines of a predominantly anti-inflammatory effect appears likely in patients with immunologicaUy mediated disease who are benefited by these drugs, since the immune response is presumably already weU established in these patients and since available evidence (25,28,29) indicates that 6-MP does not exert a significant immunosuppressive effect on an established immune response. ...
... The immunosuppressive action of 6-MP is greatest at the time of induction of the primary antibody response (2,3,25,28,29,32,33). While the macrophage and certain short-lived lymphocytes appear to play important roles in the induction phase of the immune response (34--36), long-lived mononudear cells are believed to be mainly concerned with antibody synthesis and the conservation of immunological memory (30,31). ...
Article
The mechanism of action of 6-mercaptopurine (6-MP) on an egg albumin-induced inflammatory lesion in the skin has been studied in rabbits treated with 6-MP in a daily dosage of 18 mg/kg. Relative to control animals, significant decreases in the numbers of large lymphocytes and monocytes in the blood were observed in the 6-MP-treated animals by the 9th day of treatment, without significant decrease in the numbers of polymorphonuclear leukocytes and small and medium lymphocytes. Concurrently, a significant decrease was also seen in the percentage of tissue mononuclear cells in the inflammatory skin lesion. There was a highly significant correlation between the numbers of monocytes in the blood and the per cent of mononuclear cells in the lesion. A mean of 52% of the mononuclear cells in the tissue lesion phagocytosed carbon offering further evidence that the major cell involved was the blood monocyte. In vitro incorporation of ³H-Tdr by blood mononuclear cells was significantly reduced in the 6-MP-treated animals as determined by scintillation counting and radioautography. The large lymphocyte was the predominant cell type which was labeled in vitro. Small lymphocytes and monocytes were rarely labeled. The data obtained suggest that the anti-inflammatory effect of 6-MP, reflected in these experiments by a decrease in mononuclear cells in a tissue lesion, results from suppression of a bone marrow response to local inflammation, affecting principally proliferating precursors of blood monocytes and large lymphocytes. The possible importance of this action of 6-MP in the treatment of inflammatory and immunologically mediated disease is discussed.
... However, when PCs reside in milieu providing survival niches for them, such as bone marrow (BM) and inflamed sites, they terminally differentiate into post-mitotic PCs attaining a life span of months or even decades (1). These long-lived PCs have been known to be crucial for long-lasting immunity in experimental animals and humans (2)(3)(4)(5)(6), but little is known about how they sustain viability for such a long period. ...
... The sustained presence of autoreactive long-lived PCs in peripheral lymphoid organs has the potential to exacerbate pathologic effects by several mechanisms. First, in addition to their continuous production of antibodies, these cells are refractory to immunosuppressive drugs, including steroids, cyclophosphamide, and rituximab (2,3,34). Second, they can become more active after B cell depletion therapy in some patients with autoimmune diseases (4,5). ...
Article
Full-text available
Plasma cells (PCs) are exposed to intense endoplasmic reticulum (ER) stress imposed by enormous rates of immunoglobulin (Ig) synthesis and secretion. Therefore, protein homeostasis is crucial for the survival of PCs, but its molecular mechanism remains largely unknown. Here, we found marked overexpression of FK506-binding protein 13 (FKBP13) in long-lived PCs from autoimmune mice and investigated its function using a plasmacytoma cell line secreting IgA. FKBP13 expression was induced largely in the lumen of ER in response to treatment with an ER stressor tunicamycin or overexpression of an adaptive unfolded protein response (UPR) protein X-box binding protein 1 (XBP1). Silencing of FKBP13 expression led to induction of molecules involved in the terminal UPR and ER stress-associated apoptosis. FKBP13 interacted with Ig, facilitated its ubiquitination, and lowered the extent of ER stress. FKBP13 overexpression caused a significant reduction in secreted IgA in plasmacytoma cells, and FKBP13 knockdown exerted an opposite effect. Rapamycin interfered with the interaction between FKBP13 and IgA and enhanced the amount of secreted IgA. Importantly, the level of FKBP13 was inversely correlated with the amount of secreted antibody in long-lived PCs from autoimmune mice. These results suggest that FKBP13 is a marker of long-lived PCs and a component of XBP1-dependent ER protein homeostasis. FKBP13 is likely to act as a molecular chaperone that delivers misfolded ER clients, including Ig, to ER-associated degradation, so reducing proteotoxic stress on the PC. Our data reveal a novel cytoprotective role for FKBP13 in long-lived PCs occurring at the expense of antibody production.
... As mature PCs appear as resting cells [37,38], the survival of individual PCs is critical for the maintenance of serum Ig. PCs die rapidly when isolated ex vivo due to specifi c pathways of apoptosis [39], unless they receive molecular signals that confer their survival. ...
... Studies on cells and soluble factors present in ectopic sites comprising PCs may thus help to defi ne the essential constituents of the PC niche. Conventional therapies including glucocorticoids and cytostatic drugs such as cyclophosphamide or mycopheno late motefi l have very limited impact on mature resting PCs, including autoreactive PCs [34,37,54,55]. Proteasome inhibition with bortezomib aff ecting B cells and PCs among various other cell types leads to improvement of murine SLE including suppression of anti-dsDNA production [56], whereas data from patients are still very limited [57]. ...
Article
Anti-CD20 therapy using rituximab directly targeting B cells has been approved for treatment of non-Hodgkin lymphoma, rheumatoid arthritis and anti-neutrophil cytoplasmic antibody-associated vasculitides and has led to reappreciation of B-lineage cells for anti-rheumatic treatment strategies. Moreover, blocking B-cell activating factor with belimumab, a drug that is licensed for treatment of active, seropositive systemic lupus erythematosus (SLE), represents an alternative, indirect anti-B-cell approach interfering with proper B-cell development. While these approaches apparently have no substantial impact on antibody-secreting plasma cells, challenges to improve the treatment of difficult-to-treat patients with SLE remain. In this context, anti-CD19 antibodies have the promise to directly target autoantibody-secreting plasmablasts and plasma cells as well as early B-cell differentiation stages not covered by anti-CD20 therapy. Currently known distinct expression profiles of CD19 by human plasma cell subsets, experiences with anti-CD19 therapies in malignant conditions as well as the rationale of targeting autoreactive plasma cells in patients with SLE are discussed in this review.
... 5,6 However, plasma cells are resistant to direct effects of corticosteroids consistent with lack of efficacy against established antibodies maintained by long-lived PCs (LLPCs). 7,8 Additionally, due to the broad non-specific immunosuppressive effects and non-immune side effects in various organ systems, long-term steroid use is problematic in cases where maintenance therapy is required. 9,10 In more recalcitrant situations or when more aggressive therapy is warranted to quickly mitigate clinical symptoms, antibody depletion may be attempted by apheresis. ...
Article
Full-text available
Central to protective humoral immunity is the activation of B cells and their terminal differentiation into antibody-secreting plasma cells. Long-lived plasma cells (LLPC) may survive for years to decades. Such long-lived plasma cells are also responsible for producing pathogenic antibodies that cause a variety of challenges such as autoimmunity, allograft rejection, and drug neutralization. Up to now, various therapeutic strategies aimed at durably eliminating pathogenic antibodies have failed, in large part due to their inability to efficiently target LLPCs. Several antibody-based therapies have recently gained regulatory approval or are in clinical phases of development for the treatment of multiple myeloma, a malignancy of plasma cells. We discuss the exciting potential of using these emerging cancer immunotherapies to solve the antibody problem.
... A la suite de leur formation dans la rate, les ganglions lymphatiques ou d'autres structures lymphoïdes, les plasmocytes migrent dans la moelle osseuse, où 80% de la production des anticorps sont assurés. La rate, elle, apparaît comme un réservoir mineur des LLPCs, la majorité des plasmocytes spléniques apparaissant de courte durée de vie (73). Les signaux décidant de la rétention ou de la migration des plasmocytes hors des organes lymphoïdes 29 secondaires ne sont que partiellement identifiés. ...
Article
Anti-HLA antibodies are directed against various epitopes of HLA molecules. They develop during organ transplantations, red cell transfusions or pregnancies. But anti-HLA antibodies are also detected with sensitive assays in the absence of any sensitizing event. In renal transplantation, anti-HLA antibodies, through the development of antibody-mediated rejection, represent the first cause of late allograft loss. Nevertheless, the mechanisms and the exact nature of B cells involved in anti-HLA antibodies synthesis are poorly understood.In a first part, we studied by flow cytometry in patients awaiting kidney transplantation the distribution of the different peripheral B cell subsets in relation with immunizing events, titer and diversity of anti-HLA antibodies. We also studied the serum levels of BAFF ("B cell activating factor belonging to the TNF family"), the main factor involved in survival and differentiation of mature B cells. We found an association between the presence and the diversity of anti-HLA antibodies, and the proportion of activated naive Bm2 B cells, at the expense of other subsets, independently of immunizing events. BAFF serum levels were also positively associated with the presence and the diversity of anti-HLA antibodies. These data suggest that the increase in activated naive B cells and in BAFF levels facilitate the development of anti-HLA antibodies, following an immunizing event. Similarly to what is observed in autoimmunity, BAFF could help to the positive selection of alloreactive B cell clones, in the presence of alloantigen.In a second part, we focused on the role of circulating alloreactive memory B cells in anti-HLA humoral response. To detect those alloreactive memory B cells, we used a polyclonal stimulation assay allowing the differentiation of memory B cells into plasmablasts and we studied the specificity of anti-HLA antibodies recovered from culture supernatant. A first important result was the detection, decades after an imunizing event, of specific alloreactive memory B cells, even in the absence of the antigen. The detection of those circulating alloreactive memory B cells was related to the strength of immunizing events, i.e. the number of different immunizing events in the history of patients. Indeed, patients with anti-HLA antibodies with no history of immunizing event had no circulating alloreactive memory B cells. Eventually, with HLAMatchmaker software, we showed that antibodies produced by memory B cells were directed against a limited number of epitopes shared by HLA antigens, which suggests an oligoclonality of the alloreactive memory B cell population. By comparison, serum antibodies displayed a greater diversity, with multiple epitopic specificities. These results suggest two distinct cellular arms of humoral response towards HLA epitopes: medullar plasma cells, involved in long term HLA antibodies synthesis, and memory B cells waiting for a recall response in the presence of the antigen. The factors involved in the choice of those two cellular fates are poorly understood but may involve dose and route of exposition to the alloantigen.
... Memory B cells and ASCs have been shown to be less sensitive to cyclophosphamide [1] or belimumab [2] than antigen-naïve B cell subsets. In addition, it has been demonstrated that rituximab [3] and cyclophosphamide [4] spare long-lived plasma cells. Very little is known about the impact of other drugs used to treat or to prevent lupus flares on certain B cell subsets. ...
Article
Full-text available
Introduction Clinical trials revealed a high efficacy of mycophenolate mofetil (MMF) in inducing and maintaining remission in patients with class III-V-lupus nephritis. Also extrarenal manifestations respond to MMF treatment. However, few attempts have been undertaken to delineate its mechanism of action in systemic lupus erythematosus (SLE) a disease characterized by enhanced B cell activation. Methods Clinical and paraclinical parameters of 107 patients with SLE were recorded consecutively and analyzed retrospectively. Patients were divided into treatment groups (MMF: n = 39, azathioprine (AZA) n = 30 and controls without immunosuppressive therapy n = 38). To further delineate the effect of mycophenolic acid (MPA) on naive and memory B cells in vitro assays were performed. Results Although patients taking AZA flared more frequently than patients on MMF or controls, the analysis of clinical parameters did not reveal significant differences. However, profound differences in paraclinical parameters were found. B cell frequencies and numbers were significantly higher in patients taking MMF compared to those on AZA but lower numbers and frequencies of plasmablasts were detected compared to AZA-treated patients or controls. Notably, MMF treatment was associated with a significantly higher frequency and number of transitional B cells as well as naive B cells compared to AZA treatment. Differences in T cell subsets were not significant. MPA abrogated in vitro proliferation of purified B cells completely but had only moderate impact on B cell survival. Conclusions The thorough inhibition of B cell activation and plasma cell formation by MMF might explain the favorable outcomes of previous clinical trials in patients with SLE, since enhanced B cell proliferation is a hallmark of this disease.
... In sharp contrast with our results with bortezomib, but in agreement with previous in vivo findings (22,52), we found only marginal effects of dexamethasone on plasma cell survival or function, even when added twice at 1 mM, and only on unirradiated cells. Evidently, most of the thymic plasma cells are dexamethasone-as well as radioresistant; indeed, neither treatment alone, or when combined, completely eliminated them in any of our cultures. ...
Article
Full-text available
Bortezomib is a potent inhibitor of proteasomes currently used to eliminate malignant plasma cells in multiple myeloma patients. It is also effective in depleting both alloreactive plasma cells in acute Ab-mediated transplant rejection and their autoreactive counterparts in animal models of lupus and myasthenia gravis (MG). In this study, we demonstrate that bortezomib at 10 nM or higher concentrations killed long-lived plasma cells in cultured thymus cells from nine early-onset MG patients and consistently halted their spontaneous production not only of autoantibodies against the acetylcholine receptor but also of total IgG. Surprisingly, lenalidomide and dexamethasone had little effect on plasma cells. After bortezomib treatment, they showed ultrastructural changes characteristic of endoplasmic reticulum stress after 8 h and were no longer detectable at 24 h. Bortezomib therefore appears promising for treating MG and possibly other Ab-mediated autoimmune or allergic disorders, especially when given in short courses at modest doses before the standard immunosuppressive drugs have taken effect.
... The target cell of this hormonal action remains unknown, although T helper and suppressor cells are likely to be affected. However, the known reactivity to glucocorticosteroids ofthe various types oflymphocytes ranging from sensitivity to resistance (Miller & Cole, 1967; Levine & Claman, 1970; Cohen & Claman, 1971; Gershon et aL, 1972; Liacopoulos & Ben-Efraim, 1975; Zan-Bar, Nachtigal & Feldman, 1975) makes it difficult to predict the overall action of the steroid at the cellular level in relation to antigenic competition. ...
Article
Various mechanisms for understanding antigenic competition have been proposed, such as macrophage availability, suppressor cells and their soluble products. In view of the regulatory function of some hormones on the immune system, the role of immunosuppressive adrenal corticosteroids in antigenic competition was investigated. When horse red blood cells (HRBC) were injected into rats a five-fold increase in corticosterone blood levels was measured by day 6 and a strong decrease was noted on day 11. In animals injected with HRBC and on day 6 with a second antigen (sheep red blood cells, SRBC), the corticosteroid level was high on day 11. Such high levels are immunosuppressive. To impede such increases in adrenal hormone levels, rats were adrenalectomized. Adrenalectomized or sham-operated animals receiving SRBC only showed no difference in plaque-forming cell (PFC) numbers. All sham-operated rats injected first with HRBC and 5 days later with SRBC showed the expected antigenic competition. Adrenalectomized rats also injected with both antigens sequentially had a five fold increase in number of PFC when compared with the sham-operated controls which had received both antigens. A detailed analysis of these data revealed that a proportion of adrenalectomized animals had PFC numbers within the normal range. In vitro, hydrocortisone enhances the response of spleen cells when only one antigen (SRBC) is present. Prior addition of the unrelated antigen (HRBC) impedes this enhancement. Thus, in a hydrocortisone-enriched culture medium, the presence of the first antigen can interfere with the immune response to the second unrelated antigen, mimicking in vitro a condition of antigenic competition. These findings indicate that hormones may have a role in antigenic competition.
... Therefore, although a small proportion of long-lived PCs persist in the spleen and LNs, most long-lived PCs reside in the BM. These PCs are not eliminated by treatments targeting B lineage cells, such as irradiation, prednisone, cyclophosphamide, and anti-CD20 Abs (7)(8)(9)(10). Thus, along with their persistent Ab production, the resistance of these PCs to cytostatic treatment contributes to the difficulty of resolving long-lived PC-mediated diseases. ...
Article
Full-text available
Foxp3(+) regulatory T cells (Tregs) are crucial for maintaining T cell tolerance, but their role in humoral autoimmunity remains unclear. To address this, we combined a model of autoantibody-dependent arthritis (K/BxN) with Foxp3 mutant scurfy mice to generate Treg-deficient K/BxN mice, referred to as K/BxNsf mice. The disease symptoms of K/BxNsf mice were exacerbated, and this coincided with increases in extrafollicular Th cells, follicular Th cells, and germinal centers. Surprisingly, the K/BxNsf mice exhibited an abnormal accumulation of mature plasma cells in their spleens and a corresponding loss of bone marrow plasma cells. The plasma cells were unresponsive to the bone marrow homing chemokine CXCL12, despite normal expression of the chemokine receptor CXCR4. Importantly, they were long-lived and less susceptible to the cytotoxic action of cyclophosphamide. They also expressed less FcγRIIb and were less apoptotic in response to autoantigen-autoantibody immune complexes. This suggests that Tregs control plasma cell susceptibility to cell death induced by engagement of FcγRIIb with immune complexes. Direct cytotoxic effects of Tregs also contribute to the death of plasma cells. Thus, our results reveal that Tregs suppress the emergence of long-lived splenic plasma cells by affecting plasma cell-autonomous mechanisms as well as T cell help, thereby avoiding the persistence of humoral autoimmunity.
... CYC exerts its cytotoxic effect on predominantly Blymphocytes by crosslinking DNA with alkyl groups, thus inhibiting DNA replication. Plasmablasts and plasma cells are not affected by cyclophosphamide (Miller and Cole 1967;Fassbinder et al. 2015); however, naïve B-cells are rapidly depleted (Fassbinder et al. 2015). Azathioprine (AZA) used in maintenance therapy for SLE, is a prodrug for 6-mercaptopurine, a purine analog impeding DNA synthesis via several enzymes including inosine monophosphate dehydrogenase (IMPDH). ...
Article
Full-text available
Systemic lupus erythematosus (SLE) is an autoimmune disorder with complex genetic underpinnings. This review attempts to assemble the myriad of genomic findings to build a clearer picture of the pathobiology of SLE to serve as a guide for therapeutics. Over 100 genes are now known for SLE, and several more penetrant ones have led to the emergence of more defined lupus phenotypes. Also discussed here are the targeted therapies that have come up on the horizon and the specific biologic mechanisms of more traditional therapies which have only recently been explored. The diagnostic toolbox has been enhanced by the addition of new antibodies, gene expression signatures, and mutation panels. This provides an opportunity to piece together the lupus puzzle and even revisit the clinical classification of SLE.
... Moreover, spleen and inflamed kidney could provide the survival niches to long-lived plasma cells in lupus-prone NZB/W mice [89]. The autoreactive long-lived plasma cells are resistant to conventional immunosuppressive drugs, such as dexamethasone and cyclophosphamide [90,91]. Thus, depletion of autoreactive long-lived plasma cells is crucial for developing effective therapies in SLE patients with target organ damages (Figure 3). ...
Article
Full-text available
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by excessive autoantibody production and multi-organ involvement. Although the etiology of SLE still remains unclear, recent studies have characterized several pathogenic B cell subsets and regulatory B cell subsets involved in the pathogenesis of SLE. Among pathogenic B cell subsets, age-associated B cells (ABCs) are a newly identified subset of autoreactive B cells with T-bet-dependent transcriptional programs and unique functional features in SLE. Accumulation of T-bet+ CD11c+ ABCs has been observed in SLE patients and lupus mouse models. In addition, innate-like B cells with the autoreactive B cell receptor (BCR) expression and long-lived plasma cells with persistent autoantibody production contribute to the development of SLE. Moreover, several regulatory B cell subsets with immune suppressive functions have been identified, while the impaired inhibitory effects of regulatory B cells have been indicated in SLE. Thus, further elucidation on the functional features of B cell subsets will provide new insights in understanding lupus pathogenesis and lead to novel therapeutic interventions in the treatment of SLE.
... Autoantibody-secreting plasma cells present a therapeutic problem in SLE and other autoimmune diseases because they are resistant to treatment with traditional therapies such as cyclophosphamide 74 or mycophenolate mofetil. 75 Moreover, plasma cells are resistant to the effects of B cell depletion agents such as anti-CD20 (rituximab) and anti-BAFF (belimumab). ...
Article
Numerous studies show a direct relation between circulating autoantibodies, characteristic of systemic autoimmune disorders, and primary hypertension in humans. Whether these autoantibodies mechanistically contribute to the development of hypertension remains unclear. Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder characterized by aberrant immunoglobulin production, notably pathogenic autoantibodies, and is associated with prevalent hypertension, renal injury, and cardiovascular disease. Because plasma cells produce the majority of serum immunoglobulins and are the primary source of autoantibodies in SLE, we hypothesized that plasma cell depletion using the proteasome inhibitor bortezomib would lower autoantibody production and attenuate hypertension. Thirty-week-old female SLE (NZBWF1) and control (NZW [New Zealand White]) mice were injected IV with vehicle (0.9% saline) or bortezomib (0.75 mg/kg) twice weekly for 4 weeks. Bortezomib treatment significantly lowered the percentage of bone marrow plasma cells in SLE mice. Total plasma IgG and anti-dsDNA IgG levels were higher in SLE mice compared with control mice but were lowered by bortezomib treatment. Mean arterial pressure (mm Hg) measured in conscious mice by carotid artery catheter was higher in SLE mice than in control mice, but mean arterial pressure was significantly lower in bortezomib-treated SLE mice. Bortezomib also attenuated renal injury, as assessed by albuminuria and glomerulosclerosis, and reduced glomerular immunoglobulin deposition and B and T lymphocytes infiltration into the kidneys. Taken together, these data show that the production of autoantibodies by plasma cells mechanistically contributes to autoimmune-associated hypertension and suggests a potential role for patients with primary hypertension who have increased circulating immunoglobulins.
Article
Autoantibodies are central to the pathogenesis of several autoimmune diseases including systemic lupus erythematosus. Plasma cells secrete these autoantibodies, but the anatomical sites of these cells are not well defined. Here, we found that although dsDNA-specific plasma cells in NZB/W mice were present in spleen and bone marrow, a large number were in the kidneys and their number correlated with the serum dsDNA-IgG titer. We observed renal plasma cells only in mice with nephritis, where they located mainly to the tubulointerstitium of the cortex and outer medulla. These cells had the phenotypic characteristics of fully differentiated plasma cells and, similar to long-lived bone marrow plasma cells, they were not in cell cycle. In patients with lupus nephritis, plasma cells were often present in the medulla in those with the most severe disease, especially combined proliferative and membranous lupus nephritis. The identification of the kidney as a major site of autoreactive plasma cells has implications for our understanding of the pathogenesis of lupus nephritis and for strategies to deplete autoreactive plasma cells, a long-standing therapeutic aim.
Article
Vaccination provides a powerful means to control infections. It exploits and exemplifies the ability of the immune system to preserve the information that a specific pathogen has been encountered in the past. The cells and molecular mechanisms of immunological memory are still being discussed controversially. Here, we review the current concepts of memory B cells, the signals involved in their maintenance, and their role in enhanced secondary reactions. Memory plasma cells, secreting protective antibodies over lifetime, have been recognized only recently. Their characterization as cells resting in terms of proliferation and migration, and surviving in dedicated stromal niches, in the absence of antigen, has generated new concepts of how memory cells in general are organized by stroma cells, the 'resting memory'. In autoimmunity and chronic inflammation, memory B cells and memory plasma cells can be essential players, and they require special attention, as they do not respond to most conventional therapies. Their selective targeting will depend on a molecular understanding of their lifestyle.
Article
In early-onset myasthenia gravis (EOMG), the thymus is colonized by lymph node-like infiltrates including T cell areas and germinal centers. Our Group(1) showed (1978) spontaneous anti-acetylcholine receptor (AChR) autoantibody production by EOMG thymic cells. Especially after enzymic dispersal, these are enriched in plasma cells that are evidently autonomous, long-lived, terminally differentiated and radio-resistant. Radiolabeled AChR is highly sensitive both for localizing them in situ and detecting their ongoing antibody production in culture at limiting cell numbers. Thus EOMG thymi are a readily available source of specific autoimmune human plasma cells suitable for studying their biology and testing new therapies.
Article
The late effects of various immunosuppressive insults on cell-mediated immunity in mice were studied in an attempt to assess the role of immune surveillance in the aging process. Results were obtained using susceptibility to allogeneic tumor cell challenge, graft-versus-host reaction (GVHR), blastogenic response to PHA, a thymus derived T cell-specific plant mitogen, and cytolytic activity against allogeneic tumor cells as measures of immunologic activity. In vivo studies late in life show that resistance to allogeneic tumor cells is significantly decreased in thymectomized mice, whereas those treated with cortisone, cyclophosphamide and sublethal X-ray remain unchanged. Spleen cells from only the thymectomized and the sublethally irradiated mice show reduced activity in the GVHR. No difference is seen in the activity of bone marrow cells. Results consistent with these findings were obtained in in vitro studies. Thus spleen cells from thymectomized or sublethally irradiated mice show decreased activity is response to PHA, whereas no change is seen in spleen cells from other treated groups. Hence, surgical and physical insults are more likely to induce long-lasting immunosuppression in those immunocompetent tissues whose activity normally diminishes with advancing age. Furthermore, the degree of immunosuppression seen in this study is not of the order of magnitude that one could reasonably predict a significant decrease in mean life-span.
Article
163 patients with diffuse lupus glomerulonephritis, proven by renal biopsy, were divided into four therapeutic trial groups: 67 were put on corticosteroids alone, 11 on corticosteroids and azathioprine, 32 on corticosteroids and cyclophosphamide, and 53 on corticosteroids and chlorambucil and were followed up for several years. The addition of azathioprine to corticosteroids did not increase the survival rate, improve the renal function or alter the grim prognosis of the patients. Cyclophosphamide appeared to influence favourably the pathological lesion and the renal function when added to corticosteroids, and the disease progressed at a slower rate. The fatal side effects nearly balanced the therapeutic value of cyclophosphamide. Patients on corticosteroids and chlorambucil had an excellent course. This therapeutic regimen resulted in resolution or regression of the renal pathology, marked improvement of the renal function and marked improvement of the survival rate. The authors believe that this therapeutic regimen holds the best chance of becoming the standard treatment for lupus nephritis, particularly since the side effects of chlorambucil were minimal.
Article
A 71-year-old woman presented with acutely developed symptoms of generalized lymphadenopathy, intermittent maculo-papular skin rash, pruritus, weight loss, hepato-splenomegaly, pleural exsudate and alternating breast swellings. The histopathological picture of biopsies from a lymph node and from the skin was diagnostic for immunoblastic lymphadenopathy, and the serum concentrations of IgG and IgA were increased. Delayed cutaneous hypersensitivity reactions to various antigens were totally extinguished and the number of T-lymphocytes in the peripheral blood was consistently very low. The number of both T- and B-lymphocytes further decreased during cytostatic treatment and the patient contracted numerous infections. During intermittent treatment with Levamisole the infectious episodes ceased, the cellular immune response was reestablished and the pathological hyperimmuneglobulinaemia suppressed. It is suggested that the primary immunological defect in this disease could be a failing cellular immunity, and that the hyperplasia and hyper-reactivity of the B-cell system are a secondary phenomenon.
Article
Full-text available
In vitro incubation of hyperimmune rabbit lymphoid cells with the hallucinogenic indole alkaloid, d-lysergic acid diethylamide (LSD), results in biosynthesis of modified, secretable immunoglobulin peptides. Modification involves covalent attachment of the lysergyl moiety to COOH-terminal portions of the peptides. Aalogous effects occur when cells are incubated in vitro in the presence of the non-hallucinogenic LSD analogue, d-lysergic acid, and N-[3H]-carboxymethyl-d-lysergamide. The phenomenon is reversed by tryptophan and is inhibited by puromycin and cycloheximide. In vitro attachment of the lysergyl moiety occurs in the presence of actinomycin D at levels which inhibit RNA synthesis. While LSD is not attached to intracellular tRNA, the drug binds to 80 S ribosomes from hyperimmune lymphoid cells with high affinity (K A equals 3.5 times 10-8 M-1). Similar binding occurs to nonimmune splenic ribosomes. Implications of these findings are discussed with respect to the degree of involvement of cellular protein translational mechanisms in the covalent attachment of the lysergyl moiety to low molecular weight immunoglobulin peptides.
Article
Immunosuppressive agents were given to baby guinea pigs to develop a leukocytopenic baby guinea pig model. Azathioprine in different doses, and cyclophosamide and methylprednisolone combinations did not result in predictable leukocytopenia without significant mortality. A combination of azathioprine 20 mg and cyclophosphamide 20 mg administered once daily for 5 days to 42 baby guinea pigs resulted in a mean white blood cell count of 2531/mm3 +/- 1198 (a reduction of 3931 +/- 1413 from pretreatment values). The mean counts for polymorphonuclear leukocytes and lymphocytes on day 6 were 398/mm3 and 2035/mm3, respectively. Only 7% mortality was seen in these animals. This model can be utilized to study a variety of bacterial and viral infections in "immunocompromised hosts".
Article
The effects of glucocorticosteroids on immune and inflammatory responses are reviewed. The steroids seem to change the number or function of cell receptors for regulating agents, so that in areas of inflammation: (a) blood vessels dilate less, (b) lymphocytes proliferate less, (c) all leukocytes infiltrate less, (d) macrophages become less activated (digesting and secreting less), and (e) fibroblasts produce less collagen and ground substance. In addition, the corticosteroids seem to alter the response of cells to various signals from their receptors by affecting the prostaglandin system, cyclic nucleotides, and perhaps other internal mediators.
Article
Full-text available
Bortezomib, an inhibitor of proteasomes, has been reported to reduce autoantibody titers and to improve clinical condition in mice suffering from lupus-like disease. Bortezomib depletes both short- and long-lived plasma cells; the latter normally survive the standard immunosuppressant treatments targeting T and B cells. These findings encouraged us to test whether bortezomib is effective for alleviating the symptoms in the experimental autoimmune myasthenia gravis (EAMG) model for myasthenia gravis, a disease that is characterized by autoantibodies against the acetylcholine receptor (AChR) of skeletal muscle. Lewis rats were immunized with saline (control, n = 36) or Torpedo AChR (EAMG, n = 54) in CFA in the first week of an experimental period of 8 wk. After immunization, rats received twice a week s.c. injections of bortezomib (0.2 mg/kg in saline) or saline injections. Bortezomib induced apoptosis in bone marrow cells and reduced the amount of plasma cells in the bone marrow by up to 81%. In the EAMG animals, bortezomib efficiently reduced the rise of anti-AChR autoantibody titers, prevented ultrastructural damage of the postsynaptic membrane, improved neuromuscular transmission, and decreased myasthenic symptoms. This study thus underscores the potential of the therapeutic use of proteasome inhibitors to target plasma cells in Ab-mediated autoimmune diseases.
Article
The effect of injection of the synthetic corticosteroid dexamethasone sodium phosphate upon the primary response to Escherichia coli lipopolysaccharide (LPS) was studied in mouse spleen and bone marrow. Daily corticosteroid injections, starting 1 day before immunization with LPS, could suppress the anti-LPS plaque-forming cell (PFC) response in the spleen. The higher the dose of corticosteroids, the more the splenic PFC response was suppressed. On the other hand, the bone marrow PFC response showed a dose-dependent enhancement after corticosteroid injections. This effect was maximal when tested 7 days after antigen injection, and constituted a 3- to 15-fold increase after daily injection of 16 mg dexamethasone/kg body wt. The same effect was found in genetically athymic nude mice, showing that the corticosteroid-mediated enhancement of the anti-LPS PFC response in the bone marrow is not due to elimination of T suppressor cells. Probably the differential effect of corticosteroids upon antibody formation in spleen and bone marrow is due to a redistribution of B-lineage cells, with a resulting accumulation in the bone marrow.
Article
The thiopurines, azathioprine and 6 MP are potent inhibitors of both experimental and clinical immune responses. The primary pharmacological activities are mediated by competitive inhibition of enzymes concerned with de novo purine base synthesis; Immunosuppressive activities appear to result from cytotoxic activities directed against antigen-responsive lymphocytes; this inhibition is maximal when the treatment course coincides with the proliferative expansion phase of the response. By contrast, thiopurines are comparatively ineffective if used during an effector phase of an immune response. Furthermore, administration prior to antigenic challenge does not lead to immune inhibition; in fact, it may lead to augmentation of selected immune responses. Treatment with thiopurines does not result in acute lymphopenia; prolonged courses will cause a moderate decrease in circulating lymphocytes. The drug does not selectively deplete peripheral T or B cells but can acutely reduce K (killer) cells, which are effectors in ADCC responses. In addition, short-lived thymocytes and marrow lymphocytes are rapidly depleted by these anti-metabolites. Many in vitro functions of lymphocytes, from treated animals remain normal. Recent studies indicate that, in vitro, azathioprine is specifically able to bind murine T lymphocytes; this can be shown by their ability to inhibit their capacity to rosette with sheep erythrocytes. Azathioprine is also a potent inhibitor of mixed lymphocyte culture responses and can readily suppress the in vitro generation of cytotoxic T cells. These observations suggest that drugs exert preferential toxicities for murine T cells. B lymphocytes for mice appear to vary in their susceptibility for thiopurines. By contrast, the activity of human B cells can be readily suppressed with this drug whereas T helper function is comparatively resistant. In addition to immunosuppressive properties, thiopurines are capable of exerting anti-inflammatory activities, primarily by inhibiting the replication of hematopoietic precursors.
Article
It has been suggested that germinal centers are involved in the formation of lymphocytes mediating immunological memory (115,117, 119,120,128,129,131). In this presentation we review the evidence which links the two and discuss mechanisms of cell interaction which might lead to germinal center and memory cell formation.
Article
C57BL/6 mice (H-2b) were immunized with lethally x-irradiated Moloney virus-induced lymphoma cells of BALB/c origin (H-2d) on Days 0 and 10 and received rug on Days 11 and 14. Their spleen cells were then tested for reactivity against Moloney virus-induced lymphoma of BALB/c origin by the 51Cr-release cytotoxicity assay. In non-drug-treated mice the secondary cytotoxic response was maximal on Days 14 to 15, declined rapidley, and recurred after Day 21. The cytotoxic effector cells were shown to be theta-bearing T-lymphocytes. Cyclophosphamide (CY), 180 mg/kg, given on Day 11, totally prevented the development of a cytotoxic response and when given on Day 14 abolished the response already established. CY, 48 mg/kg, as well as 1,3-bis(2-chloroethyl)-1-nitrosourea 33 mg/kg, were almost as suppressive. Immune mice given CY on Day 14 and reimmunized on Day 36 exhibited a normal tertiary response. Mice similarly immunized on Days 1 and 10 and given drugs on Day 14 were challenged on Day 15 with up to 3.5 x 10-8 viable Moloney virus-induced lymphoma cells of BALB/c origin. Despite H-2 incompatibility, all nonimmune control mice developed ascites and died, whereas all mice immunized but not given drug failed to develop ascites. By contrast, 17 of 34 immunized mice given CY, 180 mg/kg, and 7 of 34 given 1,3-bis(2-chloroethyl)-1-nitrosourea developed ascites. The ascites eventually regressed. THE RESULTS SHOW THAT CY and 1,3-bis(2-chloroethyl)-1-nitrosourea can suppress a secondary cellular immune response as measured by the T-cell-mediated 51Cr-release cytotoxicity assay in vitro and by viable tumor challenge in vivo.
Article
Sixteen patients with systemic lupus erythematosus have been observed for from 1 to 4 years while taking prednisone plus azathioprine in a dose of 2.5 mg/kg/day and compared to 19 patients with systemic lupus erythematosus managed with prednisone alone for a similar period. Patients receiving azathioprine showed a decreased mortality and morbidity, required less daily prednisone than the control group, exhibited no increased tendency to develop infection, had fewer exacerbations of their disease and maintained better renal function. Discontinuation of the azathioprine was associated with severe exacerbations of disease. The toxicity of azathioprine was minimal.
Article
The effects of glucocorticosteroids on immune and inflammatory responses are reviewed. The steroids seem to change the number or function of cell receptors for regulating agents, so that in areas of inflammation: (a) blood vessels dilate less, (b) lymphocytes proliferate less, (c) all leukocytes infiltrate less, (d) macrophages become less activated (digesting and secreting less), and (e) fibroblasts produce less collagen and ground substance. In addition, the corticosteroids seem to alter the response of cells to various signals from their receptors by affecting the prostaglandin system, cyclic nucleotides, and perhaps other internal mediators.
Article
IFN-α is known to play a critical role in the pathogenesis of systemic lupus erythematosus (SLE), but the mechanisms remain unclear. We previously showed that within weeks, exposure to IFN-α in vivo induces lupus in pre-autoimmune lupus-prone NZB×NZW F1 (NZB/W) but not in BALB/c mice. In the current study, we show that in vivo expression of IFN-α induces sustained B-cell proliferation in both BALB/c and NZB/W mice. In NZB/W but not BALB/c mice, B-cell proliferation was accompanied by a rapid and unabated production of autoantibody-secreting cells (ASCs) in secondary lymphoid organs, suggesting that a B-cell checkpoint is altered in the autoimmune background. The majority (>95%) of ASCs elicited in IFN-α-treated NZB/W mice were short-lived and occurred without the induction of long-lived plasma cells. A short course of cyclophosphamide caused a sharp drop in IFN-α-elicited short-lived plasma cells, but the levels recovered within days following termination of treatment. Thus, our work provides new insights into effectiveness and limitations of the current SLE therapies.
Chapter
Immunosuppressive drugs have two principal applications in clinical medicine. They are used in organ transplantation and autoimmune disease. The chemical suppression of the immune response has played an important part in human organ transplantation. Except where identical twins are involved, it is allogeneic grafts that are transplanted. Even with good tissue matching, there is some degree of histocompatibility difference between donor and recipient. In general, the less the histocompatibility difference the longer will be the survival of the grafted organ (van Rood, 1969; Festenstein et al., 1971; Sachs et al., 1971). Survival is further improved by the use of immunosuppressive drugs to abolish or impair the allograft rejection reaction of the recipient (Murray et al., 1963). The rationale for the use of drugs in a transplant situation is clear, and based on sound immunological considerations. In the case of autoimmune disease, however, the argument for the use of immunosuppressive drugs is less cogent. Many diseases are believed to be autoimmune in nature, that is, they are presumed to represent instances of humoral and cell-mediated immune reactivity within the body against antigenic determinants carried by normal tissue. Such an aberrant immune response against self is considered to be both initially responsible for the pathogenesis of the disease and for persisting tissue destruction during the later course of it.
Chapter
Immunosuppressant activities of drugs have been recognized since the early studies of sulfur mustards (Hektoen and Corper, 1921). Clinically, immunosuppression with adrenocorticosteroids was successfully initiated in the 1940s (Hench et al., 1949) followed by the introduction of antiproliferative drugs in systemic lupus erythematosus and other collagen diseases in the subsequent decade (Dubois, 1954; Diaz et al., 1951).
Chapter
Although it has been apparent for many years that steroid hormones exert significant influences on the growth and function of the cells of the immune system (see, for example, Dougherty, 1952), the ill-understood complexity of this system has, until recently, made it impracticable to analyse these influences further. In the last few years, however, dramatic advances in cellular immunology and immunobiology and in our understanding of the mechanisms of steroid hormone action in other tissues have begun to permit the analysis of steroid hormone effects on the immune system at the cellular and subcellular levels. In particular, much progress has been made in analysing the actions of corticosteroids, although we still know relatively little of the mechanisms or targets of sex hormone actions on this system. Nevertheless, it is now possible to incorporate much of our present knowledge into a reasonably coherent framework which should at least serve to focus attention on those areas deserving further study.
Chapter
A study of the characteristics of cell proliferation in acute leukemia has potentially three things to offer. First, we may learn the mechanism by which leukemic cells have an advantageous growth differential with respect to the normal marrow cell population. Second, information may be derived concerning the origin of the leukemic cells with particular reference to the need for continued transformation of a normal cell population. Finally, therapy for acute leukemia has been primarily directed against the parts of the cell cycle related to division, that is the synthesis of DNA and mitosis. Further information concerning the nature of the leukemic cell population may give us better methods of using current therapeutic measures and point the way toward new approaches for therapy.
Chapter
Attempts to assign biological effects of hormones on immune functions of complex organisms are difficult, because hormones are known to induce numerous changes, many of which are interrelated and simultaneously operational. Furthermore, the effects produced by many hormones are not uniform in all the mammals. Moreover, the immune response involves an intricate balance of many cellular interactions, and our knowledge of the immune system has grown tremendously. Consequently, before reviewing the effects of hormones on such a biologically complicated system, a brief review of the current understanding of normal immune functions will be presented.
Chapter
Der Herr Vorsitzende hat dem ersten Referenten dieser Sitzung die Aufgabe zugedacht, Ihnen einige zur Zeit vorherrschende Meinungen über die Verschiedenartigkeit der Lymphocyten auseinanderzusetzen und den Versuch zu unternehmen, in der Vielfalt der heute bekannten Einzelheiten ein ordnendes Prinzip zu erkennen. Die Fortschritte auf dem Gebiet der Lymphocytenforschung verdanken wir in erster Linie der Einführung neuerer Methoden, wie Cytogenetik, Immunocytochemie, Autoradiographie mit Darstellung zellständiger Makromoleküle, Techniken zur Auftrennung von Zellgemischen, Elektronenmikroskopie und enzymologischer Cytochemie. Geeignete Kombinationen solcher Techniken und ihre Anwendung beispielsweise auf zellkinetische Untersuchungen, ferner die experimentelle Entfernung von Zellen und Organen, die Ganzkörperbestrahlung zur Zerstörung des immunobiologisch aktiven Gewebes, die Behandlung mit Anti-Lymphocyten-Globulin oder cytostatischen Mitteln sowie die Organ- und Zelltransplantation haben es ermöglicht, eine große Zahl neuer Erkenntnisse zu gewinnen (Übersichten 11, 21, 40, 33). Daraus entwickelten sich hinsichtlich Herkunft und Entwicklungsmöglichkeiten der Lymphocyten gewisse Vorstellungen, zu deren besserem Verständnis wir auf einzelne phylogenetische, ontogenetische und tierexperimentelle Befunde zurückgreifen müssen. Wir wollen dabei bestrebt sein, von bisher Bekanntem über Erscheinungsformen und Funktionen der peripheren Lymphocyten auszugehen sowie erwiesene Tatsachen und Hypothesen nicht zu verwechseln.
Article
Autoantibodies are secreted by plasma cells and have an essential role in driving the renal manifestations of autoimmune diseases such as systemic lupus erythematosus and antineutrophil cytoplasmic autoantibody-associated vasculitis. Effective depletion of autoreactive plasma cells might be the key to curative treatment of these diseases. Two major plasma-cell compartments exist: short-lived plasmablasts or plasma cells, which result from differentiation of activated B cells, and long-lived plasma cells, which result from secondary immune responses. Long-lived plasma cells reside in survival niches in bone marrow and inflamed tissue and provide the basis of humoral memory and refractory autoimmune disease activity. Unlike short-lived plasmablasts, long-lived plasma cells do not respond to conventional immunosuppression or to therapies that target B cells. Existing therapies that target long-lived plasma cells, such as proteasome inhibitors and antithymocyte globulin, as well as promising approaches that target survival factors, cell homing or surface molecules, deplete the whole memory plasma cell pool, including cells that secrete protective antibodies. By contrast, we have developed a novel strategy that uses an affinity matrix to deplete pathogenic long-lived plasma cells in an autoantigen-specific manner without removing protective plasma cells. Targeting B-cell precursors to prevent replenishment of autoreactive long-lived plasma cells should also be considered.
Chapter
Local or systemic administration of phytohemagglutinin (PHA) to mice and rabbits has recently been shown to cause a sequence of striking histological changes in the peripheral lymphoid tissues [1, 2, 3]. It is fully recognized that PHA-induced blast cell formation in vivo may merely reflect the marked antigenicity of this substance and may have no bearing on the transformation phenomena observed in lymphocyte cultures. Still, the considerable rapidity and intensity of the reaction may render it a useful model system for the study of lymphocyte activation in the living animal.
Article
Immunosuppressive agents are not by and large a unique class of compounds, but are rather a variety of chemical and biological substances that share the common property of inhibiting the immune response. A knowledge of the biochemical locus of action of a new agent enables a reasonable prediction of its effectiveness as an immunosuppressant, particularly if it is known to inhibit DNA, RNA, or protein synthesis. Yet in light of the need for highly selective agents, capable of affecting only immunity to a defined antigen without general cytocidal effects, or capable of inhibiting only one element of the immune response, empiricism and the testing of a variety of different agents have a distinct place in addition to careful deductive reasoning. Biological agents, such as antibodies or antisera, that work against the types of cells involved in immunity, also require testing in a variety of immunological systems and should not be assumed to work in only one of them. Thus, antilymphocyte serum has been ascertained to inhibit cellular immunity while leaving antibody production relatively unaffected, a feature that was not readily predictable a priori.
Article
The effect of 6-mercaptopurine on the development and expression of delayed hypersensitivity was studied in the guinea pig. Results indicated that 6-MP produced its suppressive effects primarily by action on cells of the monocyte-macrophage series. Suppression could occur under conditions of both developing and pre-established delayed hypersensitivity. The defect primarily involved newly synthesized, bone marrow-derived monocytes. Marked alterations in monocyte-macrophage generation and distribution, especially the of circulating monocytes were demonstrated. Suppressive effects were associated with the appearance of a unique morphologic defect in the macrophage, that of nuclear cytoplasmic asynchrony, demonstrated by electron microscopy. Finally, the in vivo expression of delayed hypersensitivity correlated better with a variety of parameters relating to qualitative macrophage function and distribution rather than those relating to quantitative macrophage levels.
Chapter
Azathioprine (“Imuran”) is an S-substituted 6-mercaptopurine.
Article
Im nachfolgenden Beitrag sollen die Vorgänge der Regeneration, Hyperplasie und Cancerisierung am Beispiel des lymphoretikulären Systems besprochen werden. Die Berechtigung zu diesem Vorhaben, wenig mehr als 10 Jahre nach Erscheinen des Handbuchartikels von Masshoff (1955) über „die physiologische Regeneration“, ergibt sich aus dem Umstand, daß in der Zwischenzeit die Erforschung der immunbiologisch aktiven Zellsysteme umwälzende Fortschritte gebracht hat. Eine erneute Bearbeitung dieser Fragen erschien daher unumgänglich. Die Gründe für die rasche Entwicklung auf dem Gebiet der Immunologie, in deren Rahmen das lymphoretikuläre System gehört, liegen vor allem in der Verfeinerung der Untersuchungsmethoden. Es ist heute möglich, Zellen stabil zu markieren und auf diese Weise deren Schicksal zu verfolgen. Wir sind ferner in der Lage, biochemische Vorgänge auf cellulärer Ebene zu verfolgen und makromolekulare Bestandteile des Gewebes aufgrund ihrer Antigeneigenschaften immuno-histochemisch zu erfassen. Diese und weitere Gegebenheiten gestatten es, experimentell belegbare Aussagen zu machen, wo früher nur Vermutungen möglich waren. Wie wir sehen werden, haben die neu gewonnenen Erkenntnisse auch für die Beurteilung von Regeneration, Hyperplasie und Cancerisierung ihre große Bedeutung. Allerdings bleibt hervorzuheben, daß die Geschwindigkeit der heutigen wissenschaftlichen Entwicklung wenig mehr als eine Standortbestimmung zuläßt.
Article
Myasthenia gravis (MG) is treated primarily with broad-spectrum immuno-suppressants such as prednisone or azathioprine, which normally require several months to reduce autoantibody titers significantly. This delay may be caused by the resistance of the main antibody-producing cells, the plasma cells, to these drugs. In particular, long-lived plasma cells are resistant to immunosuppressive treatments and can produce (auto-) antibodies for months. Bortezomib is a proteasome inhibitor approved for treating patients with multiple myeloma, a plasma cell malignancy. Recent preclinical studies in cell cultures and animal models, and clinical studies in organ-transplant recipients, have demonstrated that bortezomib can kill non-neoplastic plasma cells within hours. This suggests that proteasome inhibitors could also be used for rapidly reducing autoantibody production in autoimmune diseases. We have begun to assess their potential in MG.
Article
Rats were given near-lethal doses of x-ray to produce clones of hemic cells marked by radiation-induced chromosome abnormalities. Subsequently, bone marrow from these rats was injected into lethally irradiated mice to form erythropoietic spleen colonies; and peripheral blood lymphocytes from the same rats were stimulated to proliferate in a mixed lymphocyte interaction (MLI), an immunological response to histocompatibility isoantigens. Chromosome markers indicated that in several instances the cells of an erythroid spleen colony and a proportion of the lymphocytes reacting in the MLI were progeny of the same stem cell in the donor rat. In addition, lymphocytes of the same radiation-marked clone were shown to proliferate in response to several different histocompatibility isoantigens. The data indicate the presence in the adult rat of a primitive lymphohematopoietic stem cell capable of yielding both erythroid and lymphoid progeny. The findings also suggest that immunological specificity is determined during lymphoid differentiation, subsequent to the stem cell stage.
Article
Full-text available
The current view holds that chronic autoimmune diseases are driven by the continuous activation of autoreactive B and T lymphocytes. However, despite the use of potent immunosuppressive drugs designed to interfere with this activation the production of autoantibodies often persists and contributes to progression of the immunopathology. In the present study, we analyzed the life span of (auto)antibody-secreting cells in the spleens of NZBNZW F1 (NZB/W) mice, a murine model of systemic lupus erythematosus. The number of splenic ASCs increased in mice aged 1-5 mo and became stable thereafter. Less than 60% of the splenic (auto)antibody- secreting cells were short-lived plasmablasts, whereas 40% were nondividing, long-lived plasma cells with a half-life of � 6 mo. In NZB/W mice and D42 Ig heavy chain knock-in mice, a fraction of DNA-specific plasma cells were also long-lived. Although antiproliferative immuno- suppressive therapy depleted short-lived plasmablasts, long-lived plasma cells survived and con- tinued to produce (auto)antibodies. Thus, long-lived, autoreactive plasma cells are a relevant target for researchers aiming to develop curative therapies for autoimmune diseases.
Article
The blood and lymphoid tissues of mice which had been injected with anti-lymphocyte globulin (A.L.G.) proved to be depleted particularly of long-lived small lymphocytes. The blood later became repopulated predominantly by shortlived small lymphocytes. This change in the composition of the circulating small-lymphocyte population, which was observed in intact animals and in mice thymectomised as adults, was not reflected in the absolute blood lymphocytecount. These findings indicate one mechanism by which A.L.G. exerts its prolonged immunosuppressive effects.
Article
Actinomycin D injected simultaneously with sheep erythrocytes in female rats caused a delay in the immune response but had no effect on the rate or maximum amount of hemagglutinin produced. The delay was roughly proportional to the concentration of the antibiotic administered, and was up to 2 days for 75 microg in a 200-gram female rat (sublethal dose for females). The dose effect in the delay in response is consistent with the time when actinomycin would no longer be available to bind with newly synthesized DNA and when messenger-RNA production could occur. Similar results were obtained with another antigen, the enzyme beta-galactosidase, in male rats during the secondary response.
Article
Lymphocytes were obtained from the thoracic duct of rats 1½ to 15 months after primary immunization with a single dose of bacteriophage ϕX 174. An intravenous injection of these lymphocytes conferred on heavily X-irradiated rats the ability to form antibody in a secondary-type manner after a first injection of ϕX. Negligible responses were obtained after cell transfer if the recipients were not challenged with antigen. Thoracic duct cells from some immunized donors were incubated in vitro for 24 hr before transfer in order to destroy selectively the large, dividing lymphocytes. The responsiveness conferred on X-irradiated recipients by such "incubated" inocula was then compared with that given by equal numbers of "fresh" thoracic duct cells. In all such comparisons the recipients of the "incubated" cells gave higher and more rapid antibody responses. It was concluded that the cells in thoracic duct lymph which carried immunological memory were small lymphocytes.
Article
Rats and mice were given a secondary immunologic stimulus with typhoid-paratyphoid A and B vaccine and then were given twice daily injections of tritiated thymidine for 4 days into the hind footpad. Thirty days later the mice were exposed to 850 rad, 500 rad or were left nonirradiated, and the rats were exposed to 850 rad or left nonirradiated. Despite a marked, generalized destruction of lymphocytes, the aortic nodes of the mice and the popliteal nodes of the rats had larger values for per cent of small lymphocytes labeled in the period immediately following irradiation than did the nodes from the nonirradiated control animals. The mean grain counts of the labeled small lymphocytes from irradiated animals were equal to or larger than those from nonirradiated animals. These results are interpreted as demonstrating a relative radioresistance of long-lived, lymph node lymphocytes. Large numbers of persistently labeled plasma cells were also found in lymph nodes after irradition. No difference could be found in the numbers or distribution of labeled plasma cells in lymph nodes from irradiated mice compared to lymph nodes from nonirradiated mice. There may have been a loss of a small proportion of the long-lived plasma cells present in the rat lymph nodes. We believe the ability of plasma cells to survive irradiation explains the radio-resistance of established antibody production.
Article
1. Splenectomy, performed one day after an intraperitoneal injection of a large dose of sheep erythrocytes, reduced the initial part of the hemolysin response, but did not significantly affect a later part. 2. The antibody-reducing effect of cortisone was significantly greater in splenectomized than in sham operated rats.
Article
(LxAF/sub 1/ hybrid mice were exposed to an LD/sub 100/ of x rays (870 n and then injected intravenously with bone marrow cells from genetically foreign (homologous) normal C/sub 3/H strain mice. It was found that the long-term survivors were still chimeras, as evidenced by the presence in the spleen of transplantation immunity isoantigens specific for the marrow donor strain (C/sub 3/H). Immunological reactivity of lymphoid tissue cells from these chimeras was assessed by their capacity, when transferred to lethaily x-irradiated (LxA)F/sub 1/ mice, to cause the rejection of homologous bone marrow. These chimera lymphoid cells brought about the rejection of marrow transplants derived from normal DBA/2 or BALB/c mice strains that are genetically foreign with respect to both the donor and host genotype of the chimeras. However, lymphoid cells from the chimeras were found to be nonreactive. i.e., tolerant. towards marrow transplants of (LxA)F/sub 1/ or of C/sub 3/H origin. Data are presented which indicate strongly the presence of immunologically reactive cells of donor (C/sub 3/H) genotype in the lymphoid tissues of these long-lived chimeras. It is suggested that a state of mutual homograft tolerance exists between the donor and host lymphoid cells in these long-lived radiation chimeras althoughmore » these cells reject grafts of cells which are homologous to both donor and host type. The implications of these findings as they relate to the phenomenon of actively acquired tolerance and to the clonal selection theory of immunity are discussed. (auth)« less
Article
The effects of 6-mercaptopurine and thioguanine on the morphologic responses of lymph nodes and spleen were studied in the rabbit. The main effect of these drugs was to inhibit the proliferation of hemocytoblasts, cells considered to be immunologically competent. Homograft rejection did not occur as long as these cells were suppressed. Rabbits which rejected their grafts in spite of continued 6-mercaptopurine treatment developed large numbers of hemocytoblasts in their lymphoid apparatus. These cells were thought to be drug resistant and analogous to resistant leukemic cells.
Article
SCINCE the grafting of organs between genetically nonidentical individuals uniformly leads to immunologic reaction against the graft and its subsequent death and rejection, successful homotransplantation requires immunologic modification of the recipient. At the time of writing such suppression of immunologic reactivity has been most readily obtained with drugs. It should be remarked at the outset that immunologic suppression either with drugs or by any other means is not a simple or well understood event. The complexity arises from the phenomenon of tolerance1 originally observed in neonatal animals by Medawar, but now recognized as occurring under a variety of circumstances in . . .
Article
UTORADIOGRAPHY has been used to study the rates of incorporation of tritiated precursors into the ribonucleic acid ( RNA ) and protein of rat lymphoid cells.'4 This technic is the only one currently available which allows such studies of individual cell types in mixed cell populations. One of us has demonstrated that the rates of incorporation of tritiated uridine ( UH�) into rat lymph node cells is an accurate reflection of the rates of RNA syn- thesis in these cells in vitro and in vivo, and that UHis incorporated into rat plasma cells at about 2 per cent of the rate of rat lymphoid blast cells!"4 Contrary to this experience with rats, human plasma cells from the thymus of a patient with systemic lupus erythematosus incorporated UHat a rapid rate in vitro!' To determine whether this was a species difference or a part of the "autoimmune" disease process in this patient, we have attempte(l to compare UHincorporation into plasma cells of other humans and various laboratory animals. One of the animals studied, the NZB mouse, develops a spontaneous autoimm one hemolytic anemia.