The effect of lead and cadmium on cell-mediated immunity was studied in peritoneal macrophages, B-, and T-lymphocytes of mice. Lead and cadmium were administered in drinking water for 10 weeks in short-term experiments and up to 18 months to deal with immune responses in aged mice. Lead and cadmium both tended to stimulate phagocytosis in peritoneal macrophages. Consequently, depressed humoral immune response could not be explained on the basis of an effect on the macrophage. The splenic B-lymphocyte response was depressed by both lead and cadmium treatment. The direct effect of these metals on B cells could account at least in part, for the suppression of the humoral immune response reported in previous studies. In long-term studies in aged mice low doses of lead (13 mg/l) tended to stimulate certain immune responses. Results obtained with higher doses (up to 1300 mg/l) were complicated by a natural immunosuppression in aged mice. As a consequence, no significant alterations were observed with high doses and the impact of Pb on the immune system in the long term cannot be predicted on the basis of this limited experimentation.

"December 1978." "Grant No. R 804200." "Project Officer Richard J. Bull, Toxicological Assessment Branch." "School of Veterinary Medicine, Oregon State University." Includes bibliographical references (pages 25-27).