Time of ART initiation in perinatally HIV-infected children impacts on HIV-specific T cell functionality

Abstract

Abstract Early initiation of antiretroviral therapy (ART) in vertically HIV-infected children provides an opportunity to limit the size of HIV reservoir. However, how the time of ART initiation impacts host HIV-specific immune responses is still poorly understood. In this study, we analyzed HIV-specific CD4 and CD8 T cell functionality in vertically HIV-infected children (age range 2.3–17.5yrs) enrolled at Bambino Gesù Children Hospital under suppressive ART and durable viral control (plasma HIV-RNA<50cp/mL). Children were designated as early treated (ET, n=8, ART initiated at age <6mo) or late treated (LT, n=7, ART initiated at age >1 year) with longer duration of ART in ET (p<0.05). Antigen-specific (CD40L+CD4+/CD107a+CD8+) T cells were evaluated in cryopreserved PBMC by flow cytometry for intracellular cytokines (IL2, IFN g, TNFα, IL21, Perforin, Granzyme B) following 12hr stimulation with GAG PTE peptides. Differences between groups were determined by Mann-Whitney t tests (P≤0.05). Frequencies of GAG-specific CD8 and CD4 T cells were not different between ET and LT. Boolean analyses revealed that CD8 T cells of LT had a higher frequency of Granzyme B+ cells compared to ET whereas CD4 T cells were qualitatively superior in ET compared to LT and exhibited higher proportions of IL2, IFNg and TNFα producing T cells and enrichment of polyfunctional T cells. Our results suggest that time of ART initiation in HIV-infected children has a long-term impact on the quality but not the quantity of the host HIV-specific T-cell immune responses. Larger studies are needed to confirm these results and to further evaluate their role in future strategies aiming at functional cure.