The present paper demonstrates that HgCl2 can affect rat peritoneal polymorphonuclear leukocyte (PMN) and macrophage (Mφ) 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 Mφ produce high levels of H2O2 when exposed to HgCl2 in vitro, whereas BN Mφ do not. Finally, mercury inhibits erythrophagocytosis of both LEW and BN "resident" peritoneal Mφ. Preliminary experiments using Mφ from other rat strains have also shown that MAXX Mφ are stimulated by HgCl2 to release H2O2 in vitro, whereas Yoshida Mφ 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 Mφ 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.
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