The percentage of PD-1 and PD-L1 expressing Treg cells is increased in HIV-infected individuals.

(A) A representative flow cytometry dot plot from an HIV-infected individual with 2000 viral RNA copies/mL blood showing the gating of effector Treg cells (eTreg: CD4+CD45RA-FOXP3hi) and resting Treg cells (rTreg: CD4+CD45RA+FOXP3lo) from a previously gated CD4 T cell population. Numbers indicate percentages of each population. (B) Percentages of PD-1+ (left panel) and PD-L1+ (right panel) Treg (including eTreg and rTreg), eTreg and rTreg cell populations in HIV-infected individuals (black circles) and healthy, uninfected controls (empty triangles). The mean ± SEM (standard error of the mean) is shown. Significant differences were determined by a Mann-Whitney U test and indicated by asterisks (*p