Expression and secretion of granzyme B by T cells is target-independent. Secretion of granzyme B by CD3⁺ (A), CD4⁺ (B), and CD8⁺ (C) T cells in the absence of target cells was assessed by ELISA after 7 days of stimulation with the different cocktails. mRNA expression of granzyme B by CD4⁺ T cells (D) was assessed by real-time PCR after 7 days of stimulation with the different stimulation combinations and in the absence of target cells. Results of 4 independent experiments are mean plus or minus SD. Comparison between groups was performed using t tests. **P < .01.