title: Anti-CD5 extends the proliferative response of human CD5+ B cells activated with anti-IgM and interleukin-2.
abstract: The CD5 T cell glycoprotein which is expressed by a subset of B cells has been shown to be involved in T cell activation and proliferation. No similar studies, to date, have addressed the role of CD5 on the B cell subset. CD5+ and CD5- B cells were sorted and stimulated with anti-CD5 monoclonal antibody (mAb) in vitro. The activation and proliferative responses of these two populations, as measured by analysis of proliferation marker, did not differ following anti-mu and interleukin (IL)-2 stimulation. The addition of anti-CD5 did not change the responsiveness of such activated CD5+ B cells but resulted in a decrease in CD25 expression. Pre-activation of B cells with phorbol 12-myristate 13-acetate, which increased CD5 expression, failed to alter the proliferative response of CD5+ B cells to anti-mu and IL-2 with or without addition of anti-CD5 mAb. Anti-mu and IL-2 treatment of CD5+ cells resulted in optimal proliferation measured at day 3 which decreased by day 6. However, addition of anti-CD5 mAb at day 3 prevented this decline in proliferative response. This dose-dependent effect was observed only when the anti-CD5 mAb was presented to the B cells in cross-linked form. Co-stimulation of CD5 did not lower the threshold of antigen to which the B cells responded. Taken together, these data support a functional role for CD5 on B cells acting as an accessory signal, following their primary activation through the B cell receptor complex and highlight differences in the role of CD5 associated with the T cell receptor complex.
authors.affiliation: Brest University Medical School, France.
authors.forename: C
authors.initials: C
authors.lastname: Jamin
authors.forename: R
authors.initials: R
authors.lastname: Le Corre
authors.forename: P M
authors.initials: PM
authors.lastname: Lydyard
authors.forename: P
authors.initials: P
authors.lastname: Youinou
mesh_terms: D000888:Antibodies, Anti-Idiotypic / Q000737:chemistry / Q000494:pharmacology*; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000494:pharmacology; D001402:B-Lymphocytes / Q000145:classification / Q000276:immunology*; D018956:CD5 Antigens / Q000276:immunology*; D002469:Cell Separation; D002648:Child; D002675:Child, Preschool; D003432:Cross-Linking Reagents; D004306:Dose-Response Relationship, Immunologic; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology*; D016130:Immunophenotyping; D007376:Interleukin-2 / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects
chemical_list: D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D018956:CD5 Antigens; D003432:Cross-Linking Reagents; D007075:Immunoglobulin M; D007376:Interleukin-2; C044203:anti-IgM