title: Germinal center T cells are distinct helper-inducer T cells.
abstract: Germinal centers (GCs) contain a significant number of CD4+ T cells, but what role these T cells may play in the development of GC B cells has not been determined. To gain insight into their role, we studied the phenotype of GC T cells and the lymphokines secreted by GC T cells isolated from human tonsils obtained after tonsillectomies. In addition to confirming that a large fraction of GC T cells are Leu-7(CD57)+ and Leu-8-, we found that they have no binding sites for peanut agglutinin. Furthermore, we found that they are CD45RA- and CD45R0+, the phenotype of helper-inducer T cells. We also found that Leu-7(CD57)+ cells display CD69, a phenotypic marker of very early cell activation, but do not display three other markers of cell activation: CD25 [interleukin-2 (IL-2) receptor], CD71 (transferrin receptor), and DR. When isolated, Leu-7(CD57)+ cells were stimulated in vitro with a mitogen that can induce peripheral blood T cells with the helper-inducer phenotype to produce various cytokines, Leu-7(CD57)+ cells did not produce IL-2, interleukin-4 (IL-4), interferon-gamma (IFN-gamma) or tumor necrosis factor-alpha (TNF-alpha) in significant amounts. Taken together, GC T cells from a distinct subpopulation of T cells with helper-inducer phenotype by their histologic location, by their surface phenotype, and by their ability to produce lymphokines. This finding is consistent with the possibility that GC T cells have been selectively recruited to actively help B cells develop in GCs.
authors.affiliation: Cross Cancer Institute, Edmonton, Alberta, Canada.
authors.forename: M B
authors.initials: MB
authors.lastname: Bowen
authors.forename: A W
authors.initials: AW
authors.lastname: Butch
authors.forename: C A
authors.initials: CA
authors.lastname: Parvin
authors.forename: A
authors.initials: A
authors.lastname: Levine
authors.forename: M H
authors.initials: MH
authors.lastname: Nahm
mesh_terms: D015703:Antigens, CD / Q000096:biosynthesis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000096:biosynthesis; D018959:CD57 Antigens; D002477:Cells; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D006684:HLA-DR Antigens / Q000096:biosynthesis; D006649:Histocompatibility Antigens / Q000096:biosynthesis; D006801:Humans; D016130:Immunophenotyping; D007371:Interferon-gamma / Q000032:analysis; D007376:Interleukin-2 / Q000378:metabolism; D015847:Interleukin-4 / Q000378:metabolism; D037181:Lectins, C-Type; D017493:Leukocyte Common Antigens; D008198:Lymph Nodes / Q000166:cytology*; D014066:Palatine Tonsil / Q000276:immunology; D010835:Phytohemagglutinins / Q000494:pharmacology; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D000099192:CD69 Antigens
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D018959:CD57 Antigens; D006684:HLA-DR Antigens; D006649:Histocompatibility Antigens; D007371:Interferon-gamma; D007376:Interleukin-2; D015847:Interleukin-4; D037181:Lectins, C-Type; D017493:Leukocyte Common Antigens; D010835:Phytohemagglutinins; D015375:Receptors, Interleukin-2; D014409:Tumor Necrosis Factor-alpha; D000099192:CD69 Antigens