PD-L1 blockade differentially increases Treg and CD8 T cell proliferative capacity depending on host viremia.

PBMC from HIV-infected individuals were stimulated with Gag peptides for 6 days in the presence of a PD-L1 blocking antibody or an isotype control antibody. Proliferation was determined by CFSE dilution (A) and alternatively by Ki67 staining (B and C). FC (fold change) in proliferation is calculated as the ratio between PD-L1 blockade conditions and isotype control conditions. Each symbol represents the result for one individual. In panels A and B, the dashed line (FC = 1) indicates no change due to PD-L1 blockade. The means of fold changes in proliferation are shown. (A) Given are the fold changes in the proliferation of Treg (including eTreg and rTreg) (black circles), CD4- (empty squares) and CD8- (empty triangles) T cell populations of different HIV-infected study groups as indicated. Significant differences in fold change of proliferation of Treg, CD4- and CD8- T cells among the 4 HIV study groups were determined using the Kruskal-Wallis test. Significant differences were found in the fold change of proliferation of Treg cells across the 4 HIV- study groups (*p 2 years of antiretroviral treatment (pre-cART and on-cART, respectively). Significant differences in fold change of proliferation between Treg, CD4- and CD8- T cells were determined by a Wilcoxon matched pairs test (*p