CYTOTOXICITY AND ACCUMULATION OF HG, AG, CD, CU, PB AND ZN IN HUMAN PERIPHERAL T-LYMPHOCYTES AND B-LYMPHOCYTES AND MONOCYTES IN-VITRO

1. The cytotoxic effects of various heavy metals were assayed by trypa n blue exclusion in vitro in human peripheral immune cells separated t o high purity. T and B lymphocytes and monocytes were equally sensitiv e to metals. The individual metals could be ranked in the following de creasing order of cytotoxic potency, Hg approximate to Ag > Cd approxi mate to Cu > Pb approximate to Zn, based on exposure time and concentr ation needed to give a particular percentage of dead cells. 2. The cyt otoxic effects became irreversible after about 13 hr of metal exposure . 3. Examination by scanning electron microscopy showed that the heavy metals caused serious destruction of the cell membranes. 4. Solubilit y and uptake of metals into the cells were studied and discussed in re lation to the cytotoxic effects. It was concluded that metal binding t o cell surfaces or precipitate formation could inhibit ordinary uptake , thereby affecting cytotoxicity. For Pb in monocytes this appeared to lead to uptake of non-toxic complexes, probably by phagocytosis.