LCMV-infected cSLP-76 KI T cells show defective effector responses in vitro. Mice were infected with LCMV Armstrong 7-10 days following tamoxifen treatment. (A) Tetramer reactivity among splenocytes from day 8 infected cSLP^+/−, cY145F, and cY112/128F mice is represented as a percent of CD8⁺YFP⁺ lymphocytes (representative of 2 independent experiments each with 5 mice per group). (B-C) Splenocytes from day 8 infected cSLP^+/−, cY145F, and cY112/128F mice were incubated in vitro with the indicated peptides and analyzed by flow cytometry. (B) Representative contour plots depict IFNγ and TNFα in YFP⁺CD8⁺ lymphocytes (representative of 2 independent experiments each with 5 mice per group). Numbers indicate the percentage of CD8⁺, TNFα IFNγ double producers over the percentage of total CD8⁺ IFNγ producers. (C) MFI of IFNγ (top panel) and IL-2 coproduction (bottom panel) were determined among CD8⁺YFP⁺ IFNγ producing splenocytes (representative of 2 independent experiments each with 5 mice per group). Bar graphs show averages ± SEM. Significant P values, when present comparing KI to WT are indicated by asterisks: ***P < .001, **P = .001-.01, *P = .01-.05.