Depletion of Treg cells by HIV-1 was associated with induction of apoptosis. Cells from spleen (A) and mLN (B) in HIV-1– or mock-infected mice were harvested; human FoxP3⁺ Treg cells and FoxP3⁻ T cells (CD45⁺CD3⁺CD8⁻) were analyzed for the expression of activated caspase-3 in the spleen and mLN. Numbers indicate percentage active caspase-3⁺ cells. Numbers in parentheses indicate relative caspase-3 signals of total CD3⁺CD8⁻FoxP3⁺ or CD3⁺CD8⁻FoxP3⁻ T cells. Summarized data of percentage of active caspase-3 of FoxP3⁺ Treg cells or FoxP3⁻ T cells in spleen (C) and mLN (D) are shown. (E-G) Induction of apoptosis in HIV-infected (p24⁺) and bystander (p24⁻) cells of FoxP3⁺ or FoxP3⁻ (CD3⁺CD8⁻) T cells. (E) FACS plots with mLN CD45⁺CD3⁺CD8⁻ T cells from mock- and HIV-infected DKO-hu mice. Numbers indicate percentage of cells in each subpopulation. Relative induction of apoptosis in p24⁺ and p24⁻ FoxP3⁺ Treg cells (F) and FoxP3⁻ T cells (G) is summarized. Data shown are representative of 3 independent experiments with at least 3 mice in each group. Error bars indicate standard errors. *P < .05.