Overproduction of cytokines in the absence of target cell death. (A–C) CBA of cytotoxic lymphocyte target cell supernatants (as in Fig. 1) in the presence or absence of QVD to block target cell death. Graphs show mouse CTL (A), human CTL (B), and mouse NK cell (C) fold change of cytokine/chemokines, and data represent mean ± SEM of three independent experiments. Statistical significance was determined by Tukey’s post-hoc ANOVA. *, P < 0.05; ^, P = 0.06.