Polyanions inhibit murine macrophage Fc receptor mediated ADCC and binding.

We examined the effect of various polyanions on mouse complement hemolytic activity, Fc receptor (FcR) subclass mediated antibody-dependent cellular cytotoxicity (ADCC) as well as binding by mouse peritoneal macrophages (M phi) of sheep erythrocyte targets. All the polyanions tested (dextran sulfate, carrageenan, polyvinyl sulfate, pentosan polysulfate and polyanethol sulfonic acid) inhibited the hemolytic activity of mouse serum complement to varying degrees. Polyanions inhibited ADCC mediated by either IgG2a or IgG2b in a reversible manner. FcR subclass mediated binding studies at 4 degrees C indicated that the various polyanions compete for FcR binding of sheep erythrocytes opsonized with murine IgG2a, IgG2b and polyclonal IgG. Polyanethol sulfonic acid was uniformly the most potent inhibitor of mouse CH50 and FcR dependent ADCC and binding functions, but did not affect C3b receptor mediated binding.