Stimulation of murine B cells with anti-Ig antibodies: dominance of a negative signal mediated by the Fc receptor.
While soluble intact rabbit anti-mouse kappa chain antibodies (RaMK) fail to stimulate [3H] thymidine incorporation in B cells of young mice, the F(ab')2 fragments thereof are stimulatory. This stimulation can be abrogated by the addition of soluble intact RaMK, pointing at the dominance of a negative signal mediated by intact antibodies, probably via their Fc portion. Blocking the interaction between intact antibody, and the Fc receptor of B cells by staphylococcal protein A renders the intact antibodies also stimulatory. Protein A itself is not mitogenic in this system nor does its addition influence B cell activation induced by rabbit F (ab')2 anti-mouse kappa chain antibodies. The data indicate that the Ig receptor of murine B cells can serve as a triggering receptor provided the negative signal mediated by cross-linkage involving the B cells' Fc receptor is avoided.
D000818:Animals; D000888:Antibodies, Anti-Idiotypic; D001402:B-Lymphocytes / Q000276:immunology*; D006041:Goats; D007140:Immunoglobulin Fab Fragments; D007145:Immunoglobulin kappa-Chains; D007148:Immunoglobulin mu-Chains; D051379:Mice; D008807:Mice, Inbred BALB C; D011817:Rabbits; D011961:Receptors, Fc; D013936:Thymidine / Q000378:metabolism
D000888:Antibodies, Anti-Idiotypic; D007140:Immunoglobulin Fab Fragments; D007145:Immunoglobulin kappa-Chains; D007148:Immunoglobulin mu-Chains; D011961:Receptors, Fc; D013936:Thymidine