CYTOLOGICAL SHIFT IN LYMPHOCYTES INDUCED BY CADMIUM IN MICE AND RATS

Hematological and clinical response such as retarded growth, polyuria and proteinuria in Cd poisoning was investigated in mice given a daily s.c. injection of sublethal doses of Cd (below 2 mg Cd/kg) for 1-7 wk and in rats exposed daily to an inhalation of CdO fumes (0.1 and 1.0 mg CdO/m3) for 4 wk. Besides a usual tendency toward neutrophilia and lymphopenia in Cd poisoning, a significant cytological shift of lymphocytes to large lymphocytes was found in Cd-treated mice and rats under extended Cd exposure. This alteration in lymphocytes was observed earlier than anemia and other responses. It was apparent 1 wk after initiation of Cd injection and was amplified when the administration was further prolonged. This cytological shift depended on the dose of Cd (0.0625-2 mg Cd/kg) at wk 1. Increased large lymphocyte counts was accompanied by decreased small lymphocyte counts and increased spleen weight. Cd may affect the immune system directly or compensatorily. Differential counts of lymphocytes could be a useful clinical indicator for early detection of adverse effect of environmental and industrial exposure to Cd.