A large fraction of the naive (CD45RO⁻) CD4⁺ T cells in IL-2–treated patients expressed the α chain of the IL-2 receptor.

(A) Median percentages and absolute counts of naive CD4⁺ T cells are shown. The hatched areas represent the fraction of cells that were CD25⁺. (B) A CD25⁺ population of naive CD4⁺ cells was identified in all groups and was largest in the IL-2+HAART group. Levels of expression of CD25 on memory (solid black lines) and naive (gray shaded histograms) CD4⁺ T cells are shown for all 3 groups. The differences in CD25 expression in the memory subsets were less consistent than the differences in the naive subset and were not significant. (C) Correlation between the number of naive CD4⁺/CD25⁺ cells and the total number of naive CD4⁺ T cells. The absolute number of naive CD4⁺/CD25⁺ cells was associated with the total number of naive CD4⁺ T cells in HIV⁻volunteers (open triangles), HAART-treated patients (gray circles), and IL-2+HAART–treated patients (black squares). Spearman rank correlation coefficients and P values are shown.