Intracellular cytokine responses to HIV-1 Gag peptide pool. Flow cytometry histograms, gated on CD3⁺CD4⁺CD8^– T cells, show the phenotype of IFN-γ⁺ cells: (A) Bcl-2 and CD38; (B) Ki-67 and TIA-1; (C) IL-2 and CD154 (CD40L); and (D) CD127 (IL-7R) and CD57. Subpopulations in quadrants are shown as percentages of CD3⁺CD4⁺CD8^– cells. Histograms are representative of 6 different subjects, all showing similar results.