The in vitro effects of mercury on peritoneal leukocytes (PMN and macrophages) from inbred brown Norway and Lewis rats.

The present paper demonstrates that HgCl2 can affect rat peritoneal polymorphonuclear leukocyte (PMN) and macrophage (M phi) functions in vitro. In addition, we have noticed that these effects of mercury vary according to the rat strain: for example, HgCl2 stimulates H2O2 release from Lewis (LEW) but not Brown Norway (BN) PMN. Similarly, LEW M phi produce high levels of H2O2 when exposed to HgCl2 in vitro, whereas BN M phi do not. Finally, mercury inhibits erythrophagocytosis of both LEW and BN "resident" peritoneal M phi. Preliminary experiments using M phi from other rat strains have also shown that MAXX M phi are stimulated by HgCl2 to release H2O2 in vitro, whereas Yoshida M phi are inhibited. Differences in lymphocyte responses (e.g. delayed-type hypersensitivity reactions and mitogen stimulation) between rats of various strains are well known. To these examples one may now add variations in PMN and M phi responses to mercury and possibly other metals. Our results suggest that caution should be exercised in interpreting the outcome of immunotoxicity studies in experimental animals. In particular, outbred rats may not provide appropriate models, that might be better obtained by comparative investigations of rats from various inbred strains.