CTL-mediated cytolysis of cognate-peptide pulsed or HIV-infected T1 cells is blocked by EGTA or CMA, but not by Brefeldin A. (A) The RT-specific CTL clone BR21 was tested for cytotoxicity against peptide-pulsed T1 cells that were either untreated (□) or pretreated with EGTA (○). Cytotoxicity was also measured during fas pathway blockade by pretreating the CTL with Brefeldin A and performing the assay in the presence of Brefeldin A (◊). (B) CTL clone BR21 was treated with medium (), CMA (⧅), Brefeldin A (⧄), or EGTA (▪) and assayed in the presence of drugs for cytotoxicity against cognate peptide-pulsed or HIV_IIIB-infected T1 cells.