Importance of oxidative metabolism in T cell cytotoxicity: a comparison of cloned T cells and spleen cells.

To distinguish between direct and indirect involvement of oxygen metabolites in CTL cytotoxicity a comparison was made of cloned CTLs and mixed cells from mouse spleen. Tumour cells could be protected from cloned CTLs and from spleen CTLs by the thiol protecting reducing agents DTT and DETC. Cytotoxic activity was inhibited by diversion of reducing power from NAD(P)H to artificial electron acceptors and by the inhibitor of NAD(P) linked enzymes cibacron blue. Although H2O2 formation could be detected during the lysis of P815 by spleen CTLs it did not prove to be a necessary requirement for cytolysis since it was not formed when glutaraldehyde-treated P815 cells were lysed. Of the scavengers of toxic oxygen metabolites tested only the hydroxyl radical scavenger sodium benzoate inhibited cytotoxicity.