Peripheral mononuclear cells enriched in CD8⁺ T cells or CD4⁺ T cells from healthy EBV-seropositive patients produce responses that are comparable with those produced by CD8⁺ T cells and CD4⁺ T cells in total PBMCs. (A) Total PBMCs from 5 healthy EBV-seropositive patients were incubated with autologous LCL (PBMC/LCL = 10:1) followed by staining for CD4 and CD8 markers and intracellular IFNγ. (B) Cells enriched in CD8⁺ or CD4⁺ T cells were incubated with autologous LCL (T cells/LCL = 10:1) in parallel with incubation of total PBMCs with autologous LCL (as in panel A) followed by intracellular staining for IFNγ. Data presented show percent of total PBMC producing IFNγ after correction for fraction of CD8⁺ and CD4⁺ T cells present in total PBMCs before enrichment.