B-cell-stimulatory factor 1 reverses Fc receptor-mediated inhibition of B-lymphocyte activation.
Intact (IgG class) rabbit anti-immunoglobulin antibodies are not mitogenic for mouse B cells but inhibit proliferation induced by F(ab')2 anti-Fab fragment antibodies (anti-Ig). In addition, cross-linkage of Fc and surface immunoglobulin receptors on B cells by intact anti-Ig inhibits inositol phospholipid breakdown (but not Ca2+ flux) resulting from ligation of antigen receptors. This system, therefore, provides a polyclonal model for B-cell inactivation by antigen-antibody complexes. T-cell-derived B-cell-stimulatory factor 1 acts synergistically with submitogenic concentrations of F(ab')2 anti-Ig to induce B-cell proliferation. We show here that B-cell-stimulatory factor 1 and intact anti-Ig also induce B cells to synthesize DNA. However, B-cell-stimulatory factor 1 does not induce inositol phospholipid breakdown, does not mobilize Ca2+ in B cells, nor does it influence the magnitude of these responses provoked by intact anti-Ig.
D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis; D006133:Growth Substances / Q000494:pharmacology*; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D015847:Interleukin-4; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D010716:Phosphatidylinositols / Q000378:metabolism; D011961:Receptors, Fc / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology
D000888:Antibodies, Anti-Idiotypic; D006133:Growth Substances; D007140:Immunoglobulin Fab Fragments; D008222:Lymphokines; D010716:Phosphatidylinositols; D011961:Receptors, Fc; D015847:Interleukin-4; D004247:DNA; D002118:Calcium