title: B-cell activation stimulated by monoclonal anti-Lyb2.1 antibody is mediated through a receptor distinct from the BSF-1 receptor.
abstract: The experiments in this paper demonstrate that monoclonal anti-Lyb2.1 antibody enhances the proliferative response of anti-immunoglobulin (anti-Ig)-stimulated but not of dextran sulfate-stimulated B cells. The magnitude of this enhanced B-cell proliferation is comparable to that induced by BSF-1 on anti-Ig-stimulated cells. The ability of this antibody to enhance B-cell proliferation does not result from its ability to neutralize the suppressive effects on B-cell activation that is mediated by the Fc fragment of anti-Ig antibody as it is equally as effective in enhancing B-cell proliferative responses stimulated by F(ab')2 fragments of anti-Ig. BSF-1 and Anti-Lyb2.1 appear to stimulate nonoverlapping pathways leading to B-cell activation since the enhanced responses induced by the combination of BSF-1 and anti-Lyb2.1 on anti-Ig-stimulated cells are additive even when maximum quantities of these activators are employed. There is also a marked difference in their activity on T cells; while BSF-1 can enhance T-cell proliferation in synergy with phorbol ester, anti-Lyb2.1 is ineffective in this regard. These data, while consistent with the suggestion that the Lyb2 surface determinant on B cells may be involved in B-cell activation, indicate that it is distinct from the receptors for BSF-1 or BCGF-II.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000950:Antigens, Ly / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D007371:Interferon-gamma / Q000494:pharmacology; D007518:Isoantibodies / Q000276:immunology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation; D051379:Mice; D011947:Receptors, Antigen, B-Cell / Q000276:immunology; D011961:Receptors, Fc / Q000502:physiology; D017452:Receptors, IgG; D011971:Receptors, Immunologic / Q000502:physiology*; D019948:Receptors, Interleukin-4; D011975:Receptors, Mitogen / Q000502:physiology*; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000950:Antigens, Ly; D007518:Isoantibodies; D008070:Lipopolysaccharides; D011947:Receptors, Antigen, B-Cell; D011961:Receptors, Fc; D017452:Receptors, IgG; D011971:Receptors, Immunologic; D019948:Receptors, Interleukin-4; D011975:Receptors, Mitogen; D007371:Interferon-gamma