Suppression of HIV infection in Tcons is mediated by Tregs. Tcons were infected with HIV and cocultured with Tregs for 3 days at a 1:1 ratio. HIV p24^Gag levels were measured by flow cytometry and ELISA. (A) Flow cytometry data from 1 representative experiment. The percentage of HIV-p24^Gag+ cells is indicated in each panel. UI indicates uninfected; INF, infected. (B) Graph showing the mean (± SEM) percentage of HIV-p24^Gag+ Tcons cultured alone or in the presence of Tregs (n = 9). (C) Levels of infection in Tcons cultured alone were considered as 100% infection. The percentage of infection of Tcons cultured with Tregs was then calculated for each donor using the equation (X = percentage of HIVp24^Gag+ Tcons cultured with Tregs × 100; percentage of HIV-p24^Gag+ Tcons cultured alone; n = 9). (D) MFI of HIV-p24^Gag determined in gated HIV-p24^Gag+ Tcons. Graph shows the mean (± SEM) MFI of the HIV-p24^Gag+ Tcons cultured alone and in the presence of Tregs (n = 6). (E-F) HIV-p24^Gag+ levels were measured by ELISA in culture supernatants collected 3 days after infection with the X4 strain (E) or the R5 strain (F) of HIV.