Cytotoxic assays using K562 cells as target cells. (A) CD3⁺ T cells, (B) CD4⁺ T cells, and (C) CD8⁺ T cells were stimulated under the indicated conditions for 7 days. After stimulation, the cells were used as effector cells in cytotoxic assays performed in an allogeneic setting using K562 cells as targets. The cells were incubated to an E/T ratio of 10:1. Cell death of CFSE-stained target cells was evaluated by FACS after 7-AAD staining. The results are presented as a percentage of specific lysis. Data from 5 independent experiments are mean plus or minus SD. Comparison between groups was performed using t tests. *P < .05; **P < .01.