Direct oxidation of lymphocytes by chromic acid does not induce blastogenesis

Blastogenic and cytotoxic effects of hexavalent chromium were evaluated by direct, 2 and 20 min oxidation of lymphocytes by 10.0 to 0.0005 mM CrO₃ at 0°C. Oxidized cells exhibited concentration-dependent cytotoxicity and the inhibition of tritiated thymidine incorporation rates. When lymphocytes were oxidized first by 1.0 mM periodic acid (H₅IO₆) and thereafter by 1.0 mM CrO₃, the viability and [³H]-TdR incorporation rates of sequentially oxidized cells were identical to the corresponding indicators of lymphocytes oxidized only by CrO₃. The reversal of the oxidation sequence restored [³H]-TdR incorporation to control levels and increased cell survival. It is therefore concluded that direct interaction of hexavalent CrO₃ with plasma membrane of lymphocytes results in concentration-dependent cytotoxicity and the inhibition of [³H]-TdR incorporation, but it does not induce blastogenesis.