Cytotoxic T lymphocyte (CTL)-mediated cytolysis proceeds in the absence of [formula omitted] antiport activity: Regulation of cytosolic pH by the [formula omitted] antiport in a cloned CTL

Abstract

Cytotoxic T lymphocyte (CTL)-mediated cytolysis of specifically bound target cells (TC) is thought to be triggered by cross-linking the T-cell antigen receptor (TcR). Biochemical events associated with TcR cross-linking include increased intracellular calcium levels [Ca 2+]i, hydrolysis of phosphatidylinositol (PI), and an increase in intracellular pH [pH]i. Whereas CTL-mediated cytolysis of some TC is calcium-dependent, and PI hydrolysis is speculated to trigger the CTL lethal hit via activation of PKC, little is known about changes in [pH]i relating to activation of the lethal hit stage. We report regulation of [pH]i in a cloned CTL by the electroneutral Na + H + antiport during activation with PMA and specific antigen-bearing TC. Furthermore, using 5-( N-methyl- N-isobutyl) amiloride (MIBA), a potent antiport inhibitor, we demonstrate that Na + H + exchange is not required for activation of CTL cytolytic activity.