Cadmium, nickel, chromium and lead accumulate in human lymphocytes and interfere with PHA-induced proliferation

The in vitro effect of five toxic metals (cadmium, lead, nickel, barium, chromium III and VI) on PHA-induced blastogenesis in human lymphocytes was investigated by [3H]-thymidine incorporation. With the exception of hexavalent chromium, the metals tested were in the chloride forms. The levels of metals associated with lymphocytes were measured under our experimental procedure. An inhibitory effect was found when cadmium was added at doses which closely approximate those of occupationally exposed subjects. Hexavalent chromium and nickel showed a biphasic pattern, with a stimulatory effect at the lowest concentrations tested (10(-8)-10(-6) mol/L) and an inhibitory effect on thymidine incorporation at concentrations higher than 10(-6) and 10(-4) mol/L, respectively. No effect was observed when lead, barium, and trivalent chromium were added to the culture medium. All metals showed the ability to enter the lymphocytes or to adhere to their surface, and the interaction appeared to be quite stable, with the exception of barium. The relationship between metal accumulation and [3H]-thymidine incorporation in the cells is discussed.