Comparison of CD25<sup>+</sup>HLA-DR<sup>+</sup> expression and CFSE<sup>dim</sup> as measures for antigen-induced activation and regulation of T cells.

<p>CFSE-labelled PBMC from 28 HIV-infected individuals were stimulated for 6 days with peptides encoding either HIV p24 consensus regions (HIV Ag) or a pool of commonly encountered non-HIV viral peptides (Non-HIV Ag). <b>A.</b> Co-expression of CD25 and HLA-DR on live CD8<sup>+</sup>CD3<sup>+</sup> T cells on non-divided CFSE<sup>high</sup> (left panel) and proliferated CFSE<sup>dim</sup> T cells (right panel), showing excessive difference in fractions of CD25<sup>+</sup>HLA-DR<sup>+</sup> in the activated subset to the right. <b>B.</b> Scatter plots of activation measured in the same culture by CFSE<sup>dim</sup> or HLA-DR<sup>+</sup>CD25<sup>+</sup>, respectively, to non-HIV (<b>+</b>) and HIV antigen (□) within the CD8<sup>+</sup> (left panel) and CD4<sup>+</sup> (right panel) T cell subsets. Significant and high correlations obtained for both Non-HIV antigens (CD8<sup>+</sup>, r = 0.92, p<0.001: CD4<sup>+</sup> r = 0.64, p<0.001) and HIV Gag p24 (CD8<sup>+</sup>, r = 0.90, p<0.001: CD4<sup>+</sup> r = 0.71, p<0.001).</p>