Figure 6. In HIV_ART subjects Breg-mediated inhibition of CD4⁺ T cell proliferation is dependent on a synergy between PD-L1 and IL-10.

Bregs or non-Bregs B cells were co-cultured for 72 hours with VPD450-labeled FACS-purified CD4⁺ T cells, activated using Anti-Biotin MACSiBead (Miltenyi, T Cell Activation/Expansion Kit) and IL-2 (2 U/ml) and proliferation of CD4+ T cells determined by flow cytometry. (a) Right panel, shows a representative overlay and right panel depicts compilation of results, whereby the reduction in proliferation is normalized to CD4⁺ T cell proliferation alone (n = 4). (b) In antibody blocking experiments, labeled and activated CD4+ T cells were co-cultured with Bregs and under conditions shown above the representative histograms (n = 4) (α-IL-10 = IL-10R blocking antibody (20 ug/ml, Biolegend), α-PD-1 = PD-1 blocking antibody (10 ug/ml, Biolegend).