Intermittent IL-2 administration leads to persistent increased CD25 expression on T lymphocytes, with transient increases in the expression of CD122 and CD132 during cycles of IL-2.

(A) CD25 expression on T cells and NK cells in HIV⁻controls, HIV⁺ patients treated with HAART, and HIV⁺ patients treated with HAART and IL-2 (contour plots). Gating was done in CD3⁺/CD4⁺ and CD3⁺/CD8⁺ in the lymphocyte gate for CD4⁺ and CD8⁺ T cells, respectively, and in CD3⁻/CD16⁺-56⁺ for NK cells. In IL-2–treated patients, very distinct CD4⁺/CD25⁺ populations were observed. Of note, a slightly decreased fluorescence intensity for CD4 was observed in the CD25⁺ cells. (B) Increase in CD25 expression on CD4⁺ T cells accompanied by transient but not persistent increases in CD122 and CD132 expression. Histograms for CD4⁺ T cells of an IL-2–treated patient before initiation of IL-2 therapy (solid gray), at the end of an IL-2 cycle (broken black), and 12 months later (solid black).