Independent ligand occupancy and cross-linking of surface Ig and Fc gamma receptors downregulates B-lymphocyte function. Evaluation in various B-lymphocyte populations.

When two distinct B-lymphocyte membrane receptors (Fc gamma R and sIg) are independently occupied by their respective multivalent ligands, inhibition of the antibody-forming cell response occurs but proliferation is not inhibited. This regulatory signal was examined in various B-lymphocyte populations. Unprimed B lymphocytes from immune deficient CBA/N and autoimmune MRL/l mice were responsive to this regulatory signal. In contrast, unprimed B lymphocytes from autoimmune NZB mice and antigen-primed B lymphocytes from normal DBA/2 mice were not. Together with previous results, these data suggest that resting B lymphocytes which have not encountered antigen are most susceptible to this regulatory signal. Lack of responsiveness to this downregulatory signal may contribute to the hyper-responsiveness of NZB B lymphocytes.