Evaluation of cytokine expression by CD4 and CD8 lymphocytes by intracellular cytokine staining. Spleen lymphocytes were isolated from mice 7 days after CVB3 infection as described in Figure 2 and cultured in medium containing PMA, ionomycin and brefeldin A for 4 hrs. Cells were labeled with antibodies to CD4 or CD8, fixed with paraformaldehyde, permeabilized and intracellularly labeled with antibodies to IFNγ [A, CD4+IFNγ+; C, CD8+IFNγ+] or IL-4 (B, CD4+IL-4+). Results represent the mean ± SEM number of CD4 or CD8 cells per spleen which are labeled positive for either cytokine. Indicated groups are either ns, not significantly different, or * significantly different at p<0.05.