Persistent T cell proliferation and MDSCs expansion precede incomplete CD4 T cell recovery in people with acute HIV-1 infection with early ART.

HIV-1 infection causes T cell dysfunction that cannot be fully restored by anti-retroviral therapy (ART). Myeloid-derived suppressor cells (MDSCs) expand and suppress T cell function during viral infection. In this study, we evaluated the dynamics of phenotypes and function of T cells and MDSCs and the effects of their interaction on CD4 T cell reconstitution in people with acute HIV-1 infection (PWAH) with early ART. Flow cytometry was used to detect the phenotypic dynamics and function of T cells and MDSCs at pre-ART, 4, 24, 48, and 96 weeks of ART. We observed that T cells were hyper-activated and hyper-proliferative in PWAH at pre-ART. Early ART normalized T cell activation but not their proliferation. T cell proliferation, enriched in PD-1 T cells, was persisted and negatively associated with CD4 T-cell counts after ART. Moreover, M-MDSCs frequency was increased and positively correlated with T cell proliferation after 96 weeks of ART. M-MDSCs persisted and inhibited T cell proliferation ex vivo, which could be partially reversed by PD-L1 blockade. Further, we found higher frequencies of proliferative CD4 T cells and M-MDSCs in PWAH with lower CD4 T cell numbers (<500 cells/μL) compared to PWAH with higher CD4 T cell numbers (>600 cells/μL) after 96 weeks of ART. Our findings indicate that persistent T cell proliferation, MDSCs expansion, and their interaction may affect CD4 T-cell recovery in PWAH with early ART.