CTLA-4 in Tregs is not the main contact-dependent mechanism. (A) Representative dot plot showing the percentage of infection in Tcons cultured alone (left), with Tregs (middle), or with Tregs in the presence of anti–CTLA-4 blocking antibody (10 μg/mL; right). (B) Graph showing the mean (± SEM) percentage of HIV-p24^Gag+ Tcons in these 3 conditions (n = 6). (C) CFSE MFI measured in Tcons cultured with Tregs in the presence or absence of anti–CTLA-4 blocking antibody (n = 5).