The human lymph node germinal center cell: characterization and isolation by using two-color flow cytometry.
ABSTRACT The germinal center of lymphoid tissues is a critical microenvironmental site of B cell activation and differentiation in response to antigenic stimuli. However, characterization of germinal center cells (GCC) in tissue sections has proved technically difficult. Therefore, we have employed two-color flow cytometric analysis of suspended human tonsillar lymphocytes in order to define more precisely the immunologic features of GCC. These cells were identified in suspension by virtue of their specific surface binding of the lectin peanut agglutinin (PNA), confirmed by tissue immunoperoxidase studies. Phycoerythrin-labeled lectin was used in combination with a variety of fluorescein-labeled antibodies in order to identify subpopulations of tonsillar lymphocytes. The majority of PNA+ cells were B cells, and both PNA+ and PNA- B cells stained for surface immunoglobulin light chains. PNA+ cells lacked surface IgD, but included cells with surface IgG and IgM. Both PNA+ and PNA- cells stained for B1, B2, BA-1, Leu-12, Leu-14, CR-I, and HLA-DR antigens, whereas CALLA was present only on PNA+ cells. There were differences between PNA+ and PNA- cells in the relative expression of B1 and B2 antigens, possibly reflecting differences in B cell activation or maturation. A small proportion of T cells were PNA+, including both helper/inducer and suppressor/cytotoxic phenotypes. PNA+ cells included both small and large lymphoid cells, and almost all DNA synthetic activity was associated with the large PNA+ cells. PNA+ B cells isolated by cell sorting had morphologic features characteristic of GCC. Therefore, PNA+ cells in suspension appeared to represent GCC, and features of these cells that cannot be convincingly shown in tissue section studies were demonstrated by flow cytometry.
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ABSTRACT: Summary Tonsillar germinal center and immunoglobulin M + (IgM+)IgD + B cells as well as peripheral blood (PB) CD5 + and CD5- (conventional) B cells from a 4-yr-old child were isolated and nudeotide sequences of expressed Ig heavy chain variable regions encoded by V.4 gene family members were determined from amplified cDNA. Whereas both tonsiUar IgM + IgD + cells and the majority of IgM-expressing CD5 + and CD5- PB B cells showed no or little somatic mutation, tonsillar germinal center (GC) B cells and IgG-expressing PB B cells carried a high load of somatic mutations in their V region genes. This suggests that somatically mutated memory B cells which have switched isotype accumulate in the PB already at young age. Their frequency seems to increase with age. On the other hand, the antibody repertoire of tonsillar IgM+IgD + B cells and the majority of IgM-expressing PB B cells is determined by germline-encoded specificities and by generation of variability in the complementary determining region III through VH-D,-J. recombination. A fraction of IgM-bearing PB B cells carries somatically mutated V region genes and probably represents GC-derived B cells which have left the GC at an early stage of the GC reaction without undergoing isotype switching. 10 V.4 germline genes were found to be expressed. Three gene segments were overrepresented in the sequence collection (35 of 50 clones): V,4.21 (30%), V71-4 (20%), and 3D279D (20%). It appears that most potentially functional V,4 germline genes are expressed in peripheral B cells. Some members of this V. gene family are dearly overrepresented over others.Annals of the New York Academy of Sciences 01/1995; 764(1):189-191. · 4.38 Impact Factor
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ABSTRACT: Light scattering properties and antigen distribution of lymphocytes labeled with the monoclonal antibodies CD 5 and CD 20 were determined for 19 patients with a chronic B-cell derived leukaemia. The density of the antigen detected by the monoclonal antibody CD 5 appeared to be considerably lower on malignant B-lymphocytes of the patients as compared with T lymphocytes. A large variation was observed in the amount of receptors for the monoclonal antibodies CD 5 and CD 20 on the malignant cells of the different patients. B-cell chronic lymphocytic leukaemia (B-CLL) patients were clearly distinguishable from leukaemic follicular non Hodgkin lymphoma patients (LF-NHL, formerly lymphosarcoma cell leukaemia) and from a patient with a prolymphocytoid transformation (PLT) of the B-CLL according to the amount of the antigens for CD 5 and CD 20. Within the B-CLL patient population, no relation of progression of the disease with distribution of these antigens could be observed. In one patient the extraordinary phenotype CD 20+, CD 11+, leu 8+, CD 5– of the malignant lymphocytes was observed. An experimentally simple method to differentiate between the various chronic lymphocytic leukaemias (CLL) appeared to be the determination of orthogonal light scattering properties of lymphocytes. In healthy donors one can always distinguish two populations of lymphocytes in the orthogonal light scatter histograms. Lymphocytes of B-CLL patients show one uniform population with a relatively small orthogonal light scattering signal, lymphocytes of our patients with PLT of B-CLL or with LF-NHL show one uniform population with a relatively large orthogonal light scattering signal.Annals of Hematology 04/1988; 56(5):201-208. · 2.40 Impact Factor
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ABSTRACT: CD10 antigen has been repeatedly detected on putative lymphoid precursor populations in both the bone marrow and circulation of multiple myeloma patients, as well as on the plasma cells in some cases of myeloma. The presence of these CD10–positive cells has raised questions regarding the ontogeny of the proliferating precursor cell in myeloma. The majority opinion has implicated a CD10-positive haemopoietic progenitor cell. However, the CD10 antigen has been detected on some mature B cells, i.e. germinal centre B cells. In this paper we postulate that the proliferating precursor cell in myeloma arises from the germinal centre. The germinal centre is the site of affinity maturation of antibody responses via somatic mutation and of isotype switching. Thus the siting of the clonogenic cell in myeloma in the germinal centre explains the overwhelming predominance of IgG and IgA myelomas, the phenomenon of point mutation which occurs in myeloma proteins in the presence of stable immunoglobulin gene rearrangements and the impaired primary immune response in myeloma. It is also consistent with the requirement for antigenic exposure in the development of myelomatosis.06/2009; 1(1):11-20.