HIV decreases Treg-cell apoptosis. (A) Depletion of CD25⁺ T cells before HIV exposure abrogates FOXP3 induction. CD4⁺ T cells from 4 individuals were either left unseparated (total) or depleted of CD25⁺ cells (depl) by negative selection, and were cultured in presence of AT-2 HIV or microvesicles. FOXP3 mRNA expression was determined at day 5. Similar results were obtained at day 3 (not shown). (B) Exposure of CD4⁺CD25⁺ T cells to AT-2 HIV decreases the number of apoptotic cells. Purified CD4⁺CD25⁺ T cells were cultured in presence of AT-2 HIV, or microvesicles for 5 days. Percentages of annexin V⁺ cells (determined in comparison with unstained controls) in 1 donor, representative of 3 donors, are shown.