Effect of CMA and Sr²⁺ on cytotoxicity mediated by HO-1. (A) HO-1 cells were preincubated with various concentrations of CMA for 2 hours. The CMA-treated or untreated HO-1 cells were then cocultured with ⁵¹Cr-labeled autologous LCL (Fas^+/+ LCL) and Fas-deficient LCL (Fas^−/− LCL), which had been loaded with the DEK-CAN peptide in the presence or absence of CMA at E:T ratios of 10:1 (▵), 5:1 (○), and 2.5:1 (□) for 4 hours. Effect of CMA on cytotoxicity mediated by alloantigen-specific CD8⁺ CTLs directed against Fas^+/+ LCL and Fas^−/− LCL was also examined. (B) HO-1 cells were preincubated with various concentrations of SrCl₂ for 18 hours. The Sr²⁺-treated or untreated HO-1 cells were then cocultured with ⁵¹Cr-labeled autologous LCL (Fas^+/+LCL) and Fas-deficient LCL (Fas^−/− LCL), which had been loaded with the DEK-CAN peptide at E:T ratios of 10:1 (▵), 5:1 (○), and 2.5:1 (□) for 4 hours. The effect of Sr²⁺ on cytotoxicity mediated by alloantigen-specific CD8⁺ CTLs directed against Fas^+/+ LCL and Fas^−/−LCL was also examined.