Strain variations in cadmium-induced suppression of lymphocyte transformation in mice

Cadmium is an environmental pollutant which has been shown in numerous studies to significantly affect immune responses. However, a review of the literature reveals many inconsistencies, both qualitative and quantitative, in the effects of cadmium on the immune system. In the present study, we examine the influence of genetic background on the effects of cadmium using lymphocyte transformation as an index of immunocompetence. Cadmium was added in vitro to mitogen and non-mitogen stimulated splenocyte cultures obtained from Balb/c, C57BL and C3HeB mice. Cadmium, 1-30 microM, was associated with a dose-dependent, linear inhibition of lymphocyte transformation in all strains. In unstimulated and Con A-stimulated cultures, the cadmium-inhibition plots were parallel but non-coincident in the three strains of mice with C57 being the most susceptible and C3H the most resistant to the inhibitory effects of cadmium. For LPS-stimulated lymphocyte transformation, the cadmium inhibition plots had different slopes in the three strains of mice suggesting a possible difference in the mechanism of action of cadmium. The relationship between these findings and cadmium-induced cytotoxicity as well as metallothionein synthesis are discussed.