ON THE CYTOTOXICITY OF IRRADIATED MEDIA - TO WHAT EXTENT ARE STABLE PRODUCTS OF RADICAL-CHAIN REACTIONS IN PHYSIOLOGICAL SALINE RESPONSIBLEFOR CELL-DEATH

In a previous publication (Czapski et al. 1992) we reported that HOCl accounts for the toxicity of irradiated phosphate-buffered saline towa rds Escherichia coli bacterial cells. We have now investigated the res pective toxicities towards lambda phage and mammalian cells. For phage , as with bacteria, cytotoxicity of the irradiated media seems to deri ve from HOCl without detectable contribution of H2O2. Mammalian cells (V79 CHO), in contrast, are more sensitive to H2O2 than to HOCl. Both agents, however, are not able to account quantitatively for the toxici ty of irradiated solutions towards V79 cells; a hitherto unidentified chlorine/oxygen derivative-being formed in the sub-micromolar concentr ation range-is suggested to be responsible for toxicity in the case of eukaryotes.