Cytolytic T lymphocyte effector function requires plasma membrane chloride flux

Treatment of cytotoxic murine T lymphocytes (CTL) with certain stilbene disulfonate derivatives results in a dose-related loss of lytic capacity. This effect is reversible and apparently not a function of drug toxicity. Additionally, CTL function is inhibited by isosmotic replacement of extracellular chloride with several relatively membrane-impermeable chloride analogues. Both inhibitory manipulations act on the effector rather than the target cell and are effective only during delivery of the lethal hit. These results suggest that delivery of the lethal hit may involve CTL exocytosis.