HIV-specific CD4 T cells express lower levels of the inhibitory molecules 2B4 and CD160 than HIV-specific CD8 T cells. (A) Expression of PD-1, 2B4, and CD160 on IFN-γ-producing HIV Gag-specific CD4 and CD8 T cells from an HIV viremic subject. (B) Statistical comparison of frequencies of HIV Gag-specific CD4 (i) and CD8 (ii) T cells that express the receptors described in panel A; analysis was performed using repeated-measures analysis of variance and Tukey post-test for pair-wise comparison. (C) Comparison of the percentage of cells that express 2B4 (i), LAG-3 (ii), and CD160 (iii) between the PD-1^high CD4 and CD8 T cells. (D) Comparison of the frequency of cells expressing 2B4 and CD160 between the PD-1^high CD4 and CD8 T cells. (E) Analysis of the expression of the inhibitory receptors on HIV- and CMV-specific CD4 and CD8 T cells; all statistics for the comparisons in panel E were performed using the Wilcoxon matched-pairs test.