CYTOTOXICITY OF SULFUR MUSTARD ON A HUMAN KERATINOCYTE CELL-LINE - DIRECT EFFECTS COMPARED TO CONDITIONED-MEDIUM EFFECTS

Direct toxic effects of sulphur mustard (SM) were compared to SM-condi tioned medium effects in a human keratinocyte cell line. Cytotoxicity was evaluated by measurement of cell viability with the Neutral Red up take assay. Cultures directly exposed to SM exhibited cytotoxic dose-r esponse curves after 24, 48 or 72 h. Inhibitory concentration 50 (IC50 ) appeared to be more than 10 times lower after 72 h than the correspo nding value after 24 h. In contrast, no cytotoxic activity was observe d in media which were collected 4 h or 24 h after SM exposure. Cell vi ability was unchanged even if observation was extended to 48 h. Result s suggested that SM cytotoxicity was not due to potential mediators se creted by human keratinocytes.