title: Cross-linking of B lymphocyte Fc gamma receptors and membrane immunoglobulin inhibits anti-immunoglobulin-induced blastogenesis.
abstract: The Fc portion of rabbit anti-mouse immunoglobulin (Ig) antibodies interferes with anti-Ig-induced B lymphocyte activation as measured by DNA synthesis on day 3 of culture or maturation to Ig-secreting cells in the presence of soluble helper factors on day 4 or 5. To investigate this Fc-dependent effect at an earlier stage in B cell activation, rabbit IgG anti-mouse mu-chain- or delta-chain-specific antibodies were compared with their F(ab')2 fragments for the ability to induce mouse B cells to undergo blast transformation, as defined by an increase in cell volume during the first 24 hr of culture. Both F(ab')2 anti-Ig reagents induce blast transformation, although F(ab')2 anti-mu antibodies induce a greater size change than F(ab')2 anti-delta antibodies. Whole anti-mu or anti-delta antibodies do not induce blast transformation; however, in the presence of a monoclonal anti-mouse Fc gamma receptor antibody that blocks IgG binding to Fc gamma receptors (Fc gamma R), whole anti-mu or anti-delta antibodies induce blast transformation as well as their F(ab')2 fragments. Because the anti-Fc gamma R antibody alone has no effect on blast transformation, it appears that the simultaneous binding of membrane IgM (or IgD) and Fc gamma R by whole anti-Ig antibodies prevents this early event in membrane Ig-induced B cell activation.
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000502:physiology*; D000911:Antibodies, Monoclonal / Q000502:physiology; D001402:B-Lymphocytes / Q000276:immunology*; D001667:Binding, Competitive; D002469:Cell Separation; D005260:Female; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D007075:Immunoglobulin M / Q000378:metabolism; D007138:Immunoglobulin delta-Chains / Q000276:immunology; D007148:Immunoglobulin mu-Chains / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D008811:Mice, Inbred DBA; D011817:Rabbits; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D011961:Receptors, Fc / Q000276:immunology / Q000378:metabolism*; D017452:Receptors, IgG
chemical_list: D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D007140:Immunoglobulin Fab Fragments; D007075:Immunoglobulin M; D007138:Immunoglobulin delta-Chains; D007148:Immunoglobulin mu-Chains; D011947:Receptors, Antigen, B-Cell; D011961:Receptors, Fc; D017452:Receptors, IgG