JAK3-AV CD8⁺ T cells produce more inflammatory/cytotoxic cytokines and display enhanced cytotoxic activity. (A) Redirected ⁵¹Cr release assay of CD8⁺ “effector” T cells incubated with allogeneic (P815) target cells at different ratios in the presence (left panel) or absence (middle panel) of anti-CD3. Syngeneic EL4 target cells (right panel) were used as a negative control. Graphs display a representative of 4 experiments performed in triplicate. Percentage of killing was calculated as decribed in “Methods.” *P < .05. (B) ELISA assay for production of IFNγ in unstimulated (unstim) or PMA/ionomycin-treated (P+I) purified CD8⁺ T cells of JAK3-WT (■) and JAK3-AV (□) mice. Data (mean ± SD) represent the average of 5 experiments performed in duplicate. (C) Intracellular staining of splenic GFP⁺CD8⁺ T cells for IFNγ and TNFα confirm the increased production of these 2 cytokines in JAK3-AV (open histogram) compared with JAK3-WT cells (shaded histogram) at a single-cell level. Bar graphs indicate the mean and SD of 3 independent experiments.