SAP^– effector CD8 and CD4 T-cell responses to chronic viral infection. Antiviral CD8 and CD4 T-cell responses were measured at day 8 after LCMV_cl13 infection (A-F). (A) LCMV-specific CD8⁺ T cells in spleen were quantified at day 8 after infection by gp33-41 D^b MHC I tetramer binding using flow cytometry. SAP^– LCMV-specific CD8 T cells were 90% more numerous (P < .03) (WT, n = 7; SAP^–, n = 8). Data were pooled from 2 independent experiments. (B) Gp33-specific CD8 T cells are also shown as percentage of total splenocytes (P < .003). (C) IFNγ and TNF production profiles of W and SAP^– CD8 T cells after 5 hours stimulation with gp33-41. (D) LCMV-specific CD4⁺ T cells in spleen were quantified by 5 hours of stimulation with the immunodominant gp61-80 I-A^b MHC II peptide and then analyzed by intracellular cytokine staining for IFNγ production. (E) Gp61-specific CD4 T cells as percentage of total splenocytes. (F) Intracellular cytokine staining for TNF and IFNγ after stimulation of day 8 post-LCMV_cl13 infection spleen cells with gp61-80 peptide. CD4⁺ gated cells are shown. (G) For comparison, CD4 T cells at day 8 after acute LCMV_arm infection. Intracellular cytokine staining for TNF and IFNγ after stimulation with gp61-80 peptide. CD4⁺ gated cells are shown. *P < .05. **P < .01. Data are representative of 4 independent experiments.