Antibody response of murine spleen cells with or without receptors for C3 to antigenic or mitogenic stimulation

Bone marrow-derived lymphocytes (B cells) with or without receptors for third component of complement (CR) were studies in their responsiveness to T-independent antigens and B-cell mitogens in terms of anti-DNP PFC response. Spleen cells were fractionated by centrifugation over a Ficoll-Hypaque density gradient after they were rosetted with antigen-antibody-complement complexes. The cells in interface fraction could not respond to any T-independent antigen tested, while they responded well to polyclonal stimulations by lipopolysaccharide and polymerized flagellin but not by keyhole limpet hemocyanin. Reduced response to T-independent antigen of the cells in interface fraction could not be explained by a shift of the kinetics, lack of number of B cells, or by the depletion of macrophages. Significance of CR in B-cell differentiation is discussed.