CuSO4 as an inhibitor of B cell proliferation

In the course of investigating the mechanisms of the in vitro immunosuppressive effect of D-penicillamine in the presence of copper ion with murine spleen cells, we observed that copper ion, by itself, exhibited a strong immunosuppressive effect at a low concentration. Namely, the addition of CuSO4 at a concentration of 0.1 to 2 microM markedly inhibited the development of SRBC-specific plaque forming cells (PFC) without causing cytotoxicity. CuSO4, at the same concentration range, suppressed the lipopolysaccharide (LPS)-induced proliferative response, but not the response induced by concanavalin A (Con A). The suppressive effect of CuSO4 on the antibody production was reversed by 500 U/ml of catalase, but that on the LPS-induced proliferative response was not. CuSO4 also substantially suppressed the pokeweed mitogen-induced proliferative response. These findings suggest that CuSO4 acts as an inhibitor of B cell proliferation and, through this effect, markedly inhibits the antibody production in murine spleen cells.