Induction of guinea pig B-cell lymphokine synthesis by mitogenic and nonmitogenic signals to Fc, Ig, and C3 receptors.

This study shows that bone marrow-derived lymphocytes of guinea pigs if appropriately activated produce a monocyte chemotactic factor (MNL CTX). Activation of B lymphocytes to produce a chemotactic lymphokine occurs subsequent to interactions with a variety of membrane-associated receptors. Polymeric B-cell mitogens with multiple binding sites, polymerized flagellin and lipopolysaccharide, initiated mediator synthesis. Furthermore, interaction of antigen-antibody complexes or aggregated gamma globulin with the Fc receptor and binding of antigen-antibody-complement complexes at the C3 receptor can effectively facilitate mediator production in the absence of a significant proliferative response. Additionally, intact anti-immunoglobulin but not its Fab fragments activated the B cells. An anti-Fab effectively converted the inactive Fab-bound B cells into producers of MNL CTX, suggesting that the basic mechanism of activation depended upon cross-linking of receptors. Thus, interaction of B-cell surface receptors such as Fc, Ig, and C3 sites with mitogenic as well as nonmitogenic molecules capable of bridging the receptors appears to trigger B-cell mediator production.