MyD88 is not required for the rapid production of effector cytokines by memory T cells. cKO and cHet mice were infected with LCMV and then treated with tamoxifen as in Figure 4. Splenocytes were isolated 60 days after LCMV infection and restimulated with the indicated LCMV-derived peptides. (A) IFNγ, TNFα, and IL-2 production by YFP⁺ CD8 T cells was assessed by intracellular staining. (B) The frequency of YFP⁺ CD8 T cells producing the indicated combinations of cytokines in response to stimulation with pooled LCMV peptide was determined. Data represent the means ± SD of 3 mice.