[Show abstract][Hide abstract] ABSTRACT: Tumor-associated B7-H1 molecules inhibit antitumor immunity in some malignancies. We found that B7-H1 expression on patient myeloma cells and human myeloma cell lines (HMCLs) was upregulated by cultivating the cells with autologous stromal cells and the human stromal cell line HS-5. Among major cytokines produced by HS-5 cells, interleukin (IL)-6-induced B7-H1 expression on HMCLs. Moreover, HS-5 cell-mediated B7-H1 expression was downregulated by inhibiting IL-6. B7-H1(+) HMCLs were more proliferative and less susceptible to antimyeloma chemotherapy compared with B7-H1(-) HMCLs. Moreover, the former cells showed higher levels of Bcl-2 and FasL expression than the latter. Finally, B7-H1 molecules on HMCLs induced T-cell apoptosis and anergy of tumor-specific T cells. Consistent with these in vitro observations, patients whose myeloma cells expressed high levels of B7-H1 had higher myeloma cell percentages in the bone marrow (BM) and higher serum lactate dehydrogenase levels compared with other myeloma patients. In addition, B7-H1 expression levels were often upregulated after myeloma patients relapsed or became refractory to therapy. Our data indicate that the BM microenvironment upregulates B7-H1 expression on myeloma cells, which links to the two biological actions of inducing T-cell downregulation and enhancing aggressive myeloma-cell characteristics. Modulating the B7-H1 pathway may be worthwhile in myeloma.Leukemia advance online publication, 17 August 2012; doi:10.1038/leu.2012.213.
Leukemia: official journal of the Leukemia Society of America, Leukemia Research Fund, U.K 07/2012; 27(2). DOI:10.1038/leu.2012.213 · 9.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Induction of immunological tolerance is dependent on the route of antigenic administration, the dose of an antigen and the age of animals.
We investigated the effect of age on the tolerance induction in mice by administration of antigen through different routes and at different doses.
Young and old BDF1 mice were orally, intraportally or intravenously administrated with a low or a high dose of ovalbumin (OVA). Then, delayed-type hypersensitivity (DTH) responses and serum anti-OVA antibody levels were assessed after systemic immunization of OVA with alum after appropriate intervals.
In the young mice, oral administration of OVA suppressed DTH response and anti-OVA IgG1, IgG2b, IgM and IgE level in a dose-dependent manner. In the old mice, however, the suppression of IgG1 and IgE levels was induced by oral administration of a low dose of OVA, but no suppression by a high dose. On the other hand, intraportal or intravenous injection of OVA did not suppress DTH response and enhanced anti-OVA antibody levels in a dose-dependent manner in both young and old mice. Production of anti-OVA IgG2a antibody after systemic injection of OVA was detected in the mice, which had been treated with intraportal or intravenous injection of OVA, but not detected in the mice, which had been treated with oral administration of OVA. On the contrary, suppression of anti-OVA IgE antibody was observed only in the mice, which had been treated with oral administration of OVA.
The oral administration of OVA, neither intravenous nor intraportal, induced immunological tolerance to OVA. An adequate dose of OVA for the tolerance induction and the suppression of antibody production are different between young and old mice. The suppression of IgE antibody was observed only by oral administration of OVA, much obviously in young mice than in the old. The results also indicated that the antigen processing in the liver did not play a major role in the induction of oral tolerance to OVA.
The Journal of Nutrition Health and Aging 05/2006; 10(3):183-91. · 2.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The hereditary conservation in the genetically encoded CD1D sequences of various primates was analyzed. Genomic CD1D sequences of 17 rhesus macaques with distinct origins, eight Indian and nine Chinese, were examined and differences of only one or two nucleotides were detected and the consensus sequence of rhesus CD1D was determined. CD1D consensus sequences of three African green monkeys (AGMs) and the rhesus monkeys were then compared to study the evolutionary differences among interspecies. The CD1D consensus sequence determined from AGMs apparently differed by seven nucleotides from the rhesus consensus sequence, and nucleotide difference induced only three amino acid changes within Exon3, corresponding to the alpha2 domain of CD1d having a hydrophobic ligand-binding pocket. Such changes in the alpha2 domain may alter the characteristics of the SIV-derived glycolipid/lipid antigens presented by each CD1d molecule to innate natural killer T cells. In addition, the CD1D genomic sequences of three chimpanzees (chimps) were determined. To our surprise, although Exon2 and Exon3 reflecting antigen-binding alpha1 and alpha2 domains in chimps' CD1D were identical to that in humans except one amino acid, three amino acids within Exon4, reflecting alpha3 domain, were distinct from humans, and one of them was identical to those in rhesus and AGM CD1D. On the basis of the findings, the evolutionary relationship of the CD1d molecules among the various primates and their HIV-1/SIV susceptibility will be discussed.
[Show abstract][Hide abstract] ABSTRACT: CD4-bearing T cells are the primary targets for human immunodeficiency virus type 1(HIV-1)/simian immunodeficiency virus (SIV) infection. However, it is unclear whether the susceptibility of CD4-bearing T cells including CD4 single positive and CD4/8 double positive T cells to HIV/SIV infection is the same or not. In this study, we compared the susceptibility to SIV infection between CD4(+) and CD4(+)8(+) T cells, using Herpesvirus saimiri (HVS)-transformed CD4(+) and CD4(+)8(+) T cells established from peripheral blood mononuclear cells (PBMC) of rhesus macaques. Although there was little difference between the two CD4-bearing T cell population in the expression level of CD4 molecules and chemokine receptors such as CXCR4 and CCR5, SIV replicated more efficiently in CD4(+)8(+) T cells than in CD4(+) T cells. Moreover, we found that reverse transcription initiated more efficiently in CD4(+)8(+) T cells than in CD4(+) T cells and that the cell lysates from CD4(+) T cells impaired the RT activity more strongly than that from CD4(+)8(+) T cells. These findings suggest that intracellular environment in CD4(+) 8(+) T cells is better for reverse transcription and that the infection of those CD4(+)8(+) T cells might play critical and different roles in HIV-1/SIV infection and dissemination.
Archives of Virology 09/2005; 150(8):1517-28. DOI:10.1007/s00705-005-0536-7 · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A nef-deleted SHIV-NM-3rN (SHIV-NI) was previously shown to be nonpathogenic and to induce protective immunity. In the present study, a SHIV-NI expressing human interferon-gamma (SHIV-IFN-gamma) was constructed and the effect of co-expression of IFN-gamma on virus replication and immunopotentiation was investigated in macaques that were vaccinated with both viruses, by comparing cytokine responses during the first 4 weeks after vaccination. Peripheral blood mononuclear cells (PBMC) isolated from vaccinated macaques were stimulated with inactivated viral particles for 24 h, and the production of IL-2, IL-4, IL-6, IL-10, IL-12, TNF-alpha and IFN-gamma was determined by ELISA and flow cytometry. All of the vaccinated macaques showed increases in cytokine production. However, the production of IFN-gamma (Th1-type cytokine) was more rapidly induced by SHIV-IFN-gamma vaccination, and IFN-gamma-producing cells appeared to be still increasing at 4 weeks after vaccination, although the difference of virus replication during the time was not significant in contrast to in vitro replication in cultured PBMC. These results suggest that co-expression of IFN-gamma with SHIV can modulate the antiviral immune responses into the Th1 type response, which would probably provide more protective immunity.
Archives of Virology 05/2004; 149(4):743-57. DOI:10.1007/s00705-003-0229-z · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Recent findings suggest macrophage-tropic HIV-1 produced in colostrum/early breast milk may have a clue to solve the mechanisms of HIV-1 transmission through breast-feeding. Here we would like to show that the majority of CD4+ cells in colostrum are CD14+ breast milk macrophages (BrMMF) expressing both chemokine receptors and DC-SIGN. Macrophage-tropic NL(AD8) HIV-1 isolate did infect such BrMMF to secrete virus particles efficiently. When stimulated with interleukin-4 (IL-4), they demonstrated a striking enhancement of DC-SIGN expression and were infected with NL(AD8) despite the apparent down-modulation of CCR5. Furthermore, although the transmissibility of NL(AD8) by unstimulated BrMMF was very weak, IL-4-simulated BrMMF showed a strong capacity to transmit the virions to their susceptible target cells, MAGIC-5, which was specifically blocked by anti-DC-SIGN-specific antibody, indicating HIV-1 particles captured by DC-SIGN but not secreted free virions may be more efficiently transmitted to other compartments such as gastrointestinal tract through acidic gastric juice.
[Show abstract][Hide abstract] ABSTRACT: We have reported previously that the cytolytic activity of murine CD8(+) cytotoxic T lymphocytes (CTL) specific for HIV-1 gp160 envelope glycoprotein was markedly inhibited by brief exposure to the free minimal antigenic peptide (I-10: 10mer peptide from gp160) by direct binding to class I MHC molecules of specific CTL in the absence of antigen-presenting cells (APC). Here, we show that treatment of such CTL with the peptide induced not only the inhibition of cytolytic activity but also IL-2Rbeta down-modulation, followed by the inhibition of IL-2-dependent growth. The peptide-mediated inhibition and restoration of expression of IL-2Rbeta were well correlated with changes in both cytolytic activity and IL-2-dependent growth of the CTL. Since enzymatic activity of granzyme B, and mRNA expression of granzyme B and perforin were significantly reduced in peptide-treated CTL, the inhibition of cytolytic activity was mainly caused by the exhaustion of cytolytic molecules. Moreover, treatment of the CTL with the epitopic peptide resulted in production of high levels of IL-2, IFN-gamma, tumor necrosis factor-alpha and MIP-1beta in the culture supernatant. Maximum amounts of cytokines were obtained in the culture supernatant when the level of cytolytic activity was the lowest. Thus, although the CTL temporarily lost their cytolytic activities, they simultaneously gained the abilities to produce cytokines for activation of various cell populations. These changes induced by free antigenic peptide in CD8(+) CTL reveal an interesting counter-regulation between their cytolytic activities and cytokine production.
International Immunology 02/2001; 13(1):43-51. · 3.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The authors studied the effects of immunosuppressive peptide cyclosporin A (CsA) on cell fusion efficiency in cells persistently infected with measles virus (448-PI-Vero cells). Treatment of 448-PI-Vero cells with 5 microM CsA enhanced the infusion. In addition, the expression of measles virus antigen on cell surface was increased by treatment with CsA. The addition of phenothiazine, an anti-calmodulin drug, enhanced the fusion of 448-PI-Vero cells in the presence of CsA, although treatment with phenothiazine alone did not affect polykaryocyte formation. The enhancement of fusion efficiency in 448-PI-Vero cells by CsA was suppressed by oligopeptide Z-D-Phe-Phe-Gly, a synthetic oligopeptide that inhibits fusion induced by measles virus. Since the cell content of major virus-specific polypeptides, such as hemagglutinin, nucleoprotein or matrix protein is the same as in untreated controls, this fusion enhancement may be related to transport and accumulation of measles virus glycoproteins.
[Show abstract][Hide abstract] ABSTRACT: An immunodominant epitope of human immunodeficiency virus-1 (HIV-1) gp160 recognized by Dd class I major histocompatibility complex (MHC) molecule-restricted, CD8+ cytotoxic T lymphocytes (CTL) was originally identified as a peptide composed of 15 amino acids (P18IIIB: RIQRGPGRAFVTIGK). However, further study has indicated that a 10-mer peptide, I-10 (RGPGRAFVTI), within P18IIIB is the minimal-sized epitope and the trimming step(s) of two carboxyl terminal amino acids (GK) is essential to produce I-10 from P18IIIB. In the processing, angiotensin-1-converting enzyme (ACE), found in sera, plays a central role in generating I-10. Target cells could be sensitized with I-10 under conditions where ACE activity in the sera was abrogated. In contrast, in the case of P18IIIB, requiring further processing to delete the C-terminus of two amino acids in order to act, sensitization of target cells was completely abrogated under the conditions. Pretreatment of target cells with brefeldin A (BFA), preventing the presentation of endogenous antigens from the class I MHC molecule pathway, did not inhibit the presentation of P18IIIB. Moreover, glutaraldehyde-fixed cells, which can not process native protein, though they could present the exogenously added peptides, were also sensitized by P18IIIB. These results clearly demonstrate that the fine processing to produce I-10 occurred in the extracellular milieu. Furthermore, our result suggests that the longer P18IIIB can bind to the class I molecules on the cell surface, and then be trimmed by ACE while it is bound. The mechanisms behind the extracellular processing outlined in this paper will offer important information for designing peptide-based vaccines to elicit MHC molecule-restricted effectors.
[Show abstract][Hide abstract] ABSTRACT: Thiobarbituric acid-reactive substances (TBARS), an index of lipid peroxidation, were assayed in postmortem brain. Basal TBARS levels were increased and oxidative stimulation produced more TBARS in AD relative to control brains. In addition, apolipoprotein E isoforms showed differing antioxidant activities, with E2 > E3 > E4, suggesting that the lowest antioxidant activity of E4 could contribute to its association with AD.
[Show abstract][Hide abstract] ABSTRACT: Are cell adhesion molecules involved in the murine model of immunologically-mediated spontaneous abortion?
Pregnant CBA/J female mice mated with DBA/2 male mice were injected with monoclonal antibodies (MAbs) to intercellular adhesion molecule-1 (ICAM-1) and leukocyte function-associate antigen-1 (LFA-1). On day 13 of gestation. viable and resorbed embryos were counted. Natural killer (NK) cell activity in the spleen, mixed lymphocyte reactions (MLR), mixed lymphocyte-placenta reactions (MLPR), and levels of interferon (IFN)-gamma were assayed.
Significant suppression of fetal resorption was observed by the injection of MAb to ICAM-1 and LFA-1. NK cell activity and the MLR anti-(CBA/J x DBA/ 2)F1 were reduced in the antibody-treated CBA/J spleen. Moreover, the level of IFN-gamma was significantly lower in the MLPR supernatants from the antibody-treated group than those of the control group.
One mechanism in the murine model of spontaneous abortion may be through the interaction of cell adhesion molecules, which may modulate NK cell activities and cytokine production.
American journal of reproductive immunology (New York, N.Y.: 1989) 04/2000; 43(3):180-5. DOI:10.1034/j.1600-0897.2000.430308.x · 2.67 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We constructed recombinant vaccinia viruses (RVV) expressing a 15-residue peptide (P18IIIB; RIQRGPGRAFVTIGK) of gp160 envelope protein from a human immunodeficiency virus type-1 (HIV-1) IIIB isolate using an H1 influenza virus hemagglutinin (HA) gene cassette. Immunofluorescent tests with antisera against both H1N1 influenza virus and P18IIIB localized chimeric HA molecules comprising influenza virus HA and P18IIIB peptide intracellularly, but the P18IIIB could not be seen on the outer surfaces of infected cells though weak fluorescence was detected regarding HA molecule. Consistent with these findings, Western blotting confirmed the expression of a polypeptide of about 74-kDa protein representing chimeric HA molecule in the infected cells. These recombinants markedly primed CD8(+) cytotoxic T lymphocytes (CTL) specific for P18IIIB as well as HA protein of the influenza virus, but failed to elicit P18IIIB-specific antibody despite stimulating production of HA-specific antibody. In addition, the P18IIIB-specific CTL could strongly lyse target cells expressing the whole HIV-1 envelope gene of IIIB strain. Thus, the influenza virus chimeric HA cassette vector system used in the present study appeared to be a useful tool for constructing vaccine candidates which will predominantly prime CD8(+) CTL specific for immunodominant determinants of various infectious agents.
Archives of Virology 02/1999; 144(8):1469-85. DOI:10.1007/s007050050604 · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Hypervariable region-1 (HVR1) from the hepatitis C virus (HCV) envelope protein is thought to be a target for neutralizing Abs. To explore HVR1 recognition by helper T cells, and their role in Ab responses, we attempted to generate helper T cells specific for HVR1 in mice of three MHC types, and with PBMC from HCV-infected HLA-diverse humans. In both species, HVR1 was presented by >1 class II MHC molecule to CD4+ helper T cells and showed surprising interisolate cross-reactivity. The epitope for two DR4+ patients was mapped to a more conserved C-terminal sequence containing a DR4 binding motif, possibly accounting for cross-reactivity. Strikingly, Abs to patients' own HVR1 sequences were found only in patients with T cell responses to HVR1, even though all had Abs to envelope protein, suggesting that induction of Abs to HVR1 depends on helper T cells specific for a sequence proximal to the Ab epitope. Thus, helper T cells specific for HVR1 may be functionally important in inducing neutralizing Abs to HCV. These results may be the first example of "T-B reciprocity," in which proximity of a helper T cell epitope determines Ab epitope specificity, in a human disease setting.
The Journal of Immunology 01/1999; 162(1):568-76. · 5.36 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The administration of corticosteroids induced apoptosis of thymocytes in vivo. Among various adhesion molecules examined, vascular cell adhesion molecule-1 (VCAM-1, CD106) was shown to be strongly expressed in these apoptotic cells. Flow cytometric analysis also showed the expression of VCAM-1 in apoptotic thymocytes. An RT-PCR study demonstrated the expression of VCAM-1 mRNA in thymocytes. Splenic lymphocytes and other lymphoid cell lines also expressed VCAM-1 during the process of apoptosis. VCAM-1 mRNA expression was also observed in RT-PCR performed on these cell lines.
[Show abstract][Hide abstract] ABSTRACT: We have observed and analyzed an unexpected cross-reactivity of CD8+ CTL between two nonhomologous peptides of the HIV-1 IIIB gp160 envelope protein, P18 (residues 315-329) and HP53 (834-848, also called TH4.1), in the context of four different class I MHC molecules, Dd, Dp, Dq (or Lq), and H-2u. In strains expressing Dd, the cross-reactivity between peptides was bidirectional, whereas in other strains (H-2u, H-2p, and H-2q), the cross-reactivity was unidirectional; that is, P18-specific CTLs showed no killing against targets pulsed with HP53, although HP53 stimulated CTL showed cross-reactive lysis against P18-pulsed target cells. Cross-reactivity was also shown in immunization in vivo and with target cells endogenously expressing viral protein in vitro using two different recombinant vaccinia viruses expressing only the N-terminal portion of gp160, containing P18 but not HP53. Peptide cross-contamination was excluded. Cold target inhibition and single cell cloning experiments indicated that the same CTL was responding to both peptides. Using substituted and truncated peptides, we explored amino acid residues critical for cross-reactive CTL recognition, identified fine specificity similarities among all cross-reactive CTL lines but not non-cross-reactive lines, and mapped cross-reactivity to a 10-residue core of P18 and to an eight-residue core of HP53. A comparison of these peptide sequences and recent data on residues of P18 interacting with H-2Dd provided us with clues to residues involved in the interaction of the CTL with the MHC-peptide complex.
The Journal of Immunology 12/1996; 157(10):4399-411. · 5.36 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Free peptide has been found to inhibit cytotoxic T lymphocyte (CTL) activity, and veto cells bearing peptide-major histocompatibility complex (MHC) complexes have been found to inactivate CTL, but the two phenomena have not been connected. Here we show that a common mechanism may apply to both. CD8+ CTL lines or clones specific for a determinant of the human immunodeficiency virus (HIV) 1 IIIB envelope protein gp160, P18IIIB, are inhibited by as little as 10 min exposure to the minimal 10-mer peptide, I-10, within P18IIIB, free in solution, in contrast to peptide already bound to antigen-presenting cells (APC), which does not inhibit. Several lines of evidence suggest that the peptide must be processed and presented by H-2Dd on the CTL itself to the specific T cell receptor (TCR) to be inhibitory. The inhibition was not killing, in that CTL did not kill 51Cr-labeled sister CTL in the presence of free peptide, and in mixing experiments with CTL lines of different specificities restricted by the same MHC molecule, Dd, the presence of free peptide recognized by one CTL line did not inhibit the activity of the other CTL line that could present the peptide. Also, partial recovery of activity could be elicited by restimulation with cell-bound peptide, supporting the conclusion that neither fratricide nor suicide (apoptosis) was involved. The classic veto phenomenon was ruled out by failure of peptide-bearing CTL to inactivate others. Using pairs of CTL lines of differing specificity but similar MHC restriction, each pulsed with the peptide for which the other is specific, we showed that the minimal requirement is simultaneous engagement of the TCR and class I MHC molecules of the same cell. This could occur in single cells or pairs of cells presenting peptide to each other. Thus, mechanistically, the inhibition is analogous to veto, and might be called self-veto. As a clue to a possible mechanism, we found that free I-10 peptide induced apparent downregulation of expression of specific TCR as well as interleukin 2 receptor, CD69, lymphocyte function-associated antigen 1, and CD8. This self-veto effect also has implications for in vivo immunization and mechanisms of viral escape from CTL immunity.
Journal of Experimental Medicine 04/1996; 183(3):879-89. DOI:10.1084/jem.183.3.879 · 13.91 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the present study, we characterized the epitope of a monoclonal antibody against purified amyloid plaque cores (Am-3). By immunocytochemical experiments, Am-3 stained cerebrovascular and senile plaque amyloid in brain sections of patients with Alzheimer's disease (AD) in a similar manner to that of antibodies against amyloid beta-protein (A beta). By Western blotting experiments, Am-3 recognized only a 35 kDa protein, which was revealed to be glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and not A beta or beta amyloid precursor protein (beta PP). However, Am-3 recognized both GAPDH and purified native A beta in a dot-binding assay. Therefore, we concluded that Am-3 recognized both GAPDH and native A beta. Other monoclonal antibodies (6C6 and AmT-1) against the synthetic peptide corresponding to residues 1-28 of A beta also recognized these proteins. Because the amino acid sequences of these two proteins are not homologous, we propose that the crossreactivity between A beta and GAPDH is a consequence of their similar conformational epitopes. The possibility of crossreactions would complicate immunochemical and immunocytochemical studies of brain aging, AD and Down's syndrome. The implications of crossreactivity in developing immunological assays and in investigating the amyloid deposits of AD are discussed.
Neurobiology of Aging 11/1995; 17(3):405-14. · 4.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Expression of protein tyrosine kinase (PTK) was evaluated and compared between cortical and medullary thymic epithelial cell (TEC) lines, TEC 14C18 and TEC1C6, respectively. Reverse transcription-polymerase chain reaction (RT-PCR) methods using degenerate primers for conserved sequence in catalytic domain of PTK revealed the expression of 13 kinds of PTKs in these cell lines. These PTKs included 6 receptor and 7 non-receptor types. In the next step, we compared the intensity of mRNA expression level of these kinases between cortical and medullary TEC lines. Tyrosine kinases of receptor type were differentially expressed between cortical and medullary TEC lines; e.g., mRNA expression of flg was observed more intensively in the cortical TEC line than in the medullary one, while mRNA expression of bek, met and sky was vice versa. On the other hand, expression of non-receptor tyrosine kinases, including four JAK-tyk family members, are comparable in both lines. These results suggested that these PTKs, especially of receptor type, might play an important role in the development of the thymic microenvironment.
Biochemical and Biophysical Research Communications 09/1995; 213(3):768-73. DOI:10.1006/bbrc.1995.2196 · 2.28 Impact Factor