Defective TCR-dependent proliferation and cytokine production in r1ΔT/r2n T cells. (A) Shown 60 hours after stimulation, CFSE-labeled purified T cells were gated on CD4 or CD8, and the histograms were overlaid between genotypes. Above each FACS plot are numbers showing the percentage of cells in each division, with the rightmost number indicating the nondivided population. (B) Thymidine incorporation assays of stimulated r1f/r2n (Cre⁻) or r1ΔT/r2n (Cre⁺) purified T cells. Stimuli used were anti-CD3 alone (i), anti-CD3 plus IL-2 (ii), anti-CD3 plus anti-CD28 (iii), and PMA plus onomycin (iv). Data are shown as the mean ± SEM of triplicate wells from a representative experiment. (C) Cell-size profile of 60-hour–stimulated Cre⁻ or Cre⁺ cells. The mean forward scatter of live cells is included on each dot plot. (D) ELISA quantification of IL-2 and IFN-γ in supernatants of r1f/r2n (Cre⁻) or r1ΔT/r2n (Cre⁺) CD4⁺ T cells stimulated for 48 hours. Data are shown as the mean ± SEM of 3 independent experiments comparing Cre⁻ and Cre⁺ T cells. (E) Intracellular stain for p85α in anti-CD3/anti-CD28–stimulated Cre⁻ and Cre⁺ purified T cells. Dot plot of forward scatter versus p85α is shown. Data are representative of at least 3 independent experiments.