Down-modulation of CD7 expression in CD8 T cells in patients infected with HIV-1. (A) PBMCs from healthy adult blood donors and adult patients infected with HIV-1 were stained with monoclonal antibodies, including CD7. Data in plots are gated on CD8 T cells. Numbers in figure indicate percentage of cells within the 3 gates. The bar chart (B) represents accumulative data from uninfected healthy blood donors (n = 23) and subjects infected with HIV-1 (n = 17); ^**P < .001; ^*P < .005. Statistical analysis: independent samples t test. Mean and standard error is shown. (C) The expression of CD27 and CD28 splits the CD7^low and CD7^negative CD8 T-cell subsets into separate subpopulations.