RELATIONSHIP BETWEEN CELLULAR GLUTATHIONE LEVEL AND SUSCEPTIBILITY TOLAK KILLING IN HUMAN PHARYNGEAL CARCINOMA CELL-LINE

We examined the relationship between 2 cellular glutathione re (GSH) l evel and susceptibility to lymphokine-activated killer (LAK) cell-medi ated cytolysis in KB human pharyngeal carcinoma cells. Treatment of KB cells with D,L-buthionine-S,R-sulfoximine (BSO), a gamma-glutamyl cys teine synthetase blocker; resulted in decreased total intracellular GS H levels associated with increased susceptibility to LAK killing. In c ontrast, treatment with oxothiazolidine-4-carboxylate (OTZ, a precurso r of cysteine), which is known to increase cellular GSH level, decreas ed the susceptibility of KB cells to LAK killing. Both agents had no e ffects on binding frequency of KB cells to LAK cells. These results su ggest that intracellular GSH in tumor cells play a protective role aga inst LAK mediated cytolysis, specially in the post-binding killing pha se.