CD39 activity plays a role in the Treg-suppressive activity of HIV infection. Tregs and Tcons were stained with anti–CD39PE-Cy7 and anti–CD73-APC after 3 days of coculture and analyzed by flow cytometry. (A) CD39 and CD73 expression of 1 representative individual. (B) Graph showing the mean (± SEM) percentage of CD39⁺ (left) and CD73⁺ (right) cells (n = 4). (C) Infected Tcons cultured alone or with Tregs in presence or absence of either an anti-CD39 blocking antibody or a matched isotype control. Tregs were loaded with calcein AM before culture. Graph shows the mean (± SEM) percentage of suppression of HIV infection after the addition of the anti-CD39 blocking antibody or the matched isotype control (n = 3). (D) Infected Tcons cultured in the presence or absence of anti-CD39 blocking antibody (10 μg/mL). Graph shows the mean (± SEM) percentage of HIV-p24^Gag+ Tcons (n = 3). (E) Graph showing the MFI of CFSE, Ki67, and cyclin B staining in gated Tcons after their culture with Tregs treated or not with anti-CD39 (n = 4).