Effect of ascorbic acid on killing of lymphocytes and macrophages by hydrogen peroxide

The ability of ascorbic acid (AA) to modify the H2O2 (0.6 to 9 mM) toxic activity for human lymphocytes (PBMC) and murine peritoneal macrophages (PM) was studied in vitro. 100 microM AA added simultaneously with H2O2 to the cell medium enhanced the killing of PBMC but not of PM independently of the presence of Fe(2+)-EDTA. Similarly, preincubation of PBMC with 500 microM AA that resulted in a 2.5-fold rise in the intracellular level of AA increased their susceptibility to both H2O2 and H2O2-Fe(2+)-EDTA. On the contrary, PM preincubated with AA were more resistant to the toxic action of the H2O2-Fe(2+)-EDTA system and did not reveal any changes of the susceptibility to H2O2 alone. It is suggested that AA under certain conditions may have opposite effects on the H2O2-induced cell damage related to inflammation.