Decreased frequency of CD73+CD8+ T cells of HIV-infected patients correlates with immune activation and T cell exhaustion

Recent studies indicate that murine Tregs highly express the ENTDP1, as well as the 5=-NT and thereby, suppress Teff function by extracellular adenosine production. Furthermore, CD73 seems to play a role as costimulatory molecule for T cell differentiation. In this study, we analyzed the expression of CD73 on peripheral and lymph nodal Teffs and Tregs in a cohort of 95 HIV patients at different stages of disease, including LTNP and ECs. In contrast to murine Tregs, CD73 was only expressed on a small minority (10%) of peripheral Tregs. In contrast, we see high expression of CD73 on peripheral CD8 T cells. In HIV infection, CD73 is markedly reduced on all Teffs and Tregs, regardless of the memory subtype. On CD8 T cells, a positive correlation between CD73 expression and CD4 counts (P0.0003) was detected. CD73 expression on CD8 T cells negatively correlated with HLA-DR (0.0001) and PD1 (P0.0457) expression. The lower CD73 expression on CD8 T cells was partially reversible after initiation of ART (P0.0016). Functionally, we observed that CD8CD73 T cells produce more IL-2 upon HIV-specific and unspecific stimulation than their CD73 counterparts and show a higher proliferative capacity. These data indicate that down-regulation of CD73 on CD8 T cells correlates with immune activation and leads to functional deficits in HIV infection. J. Leukoc. Biol. 94: 000–000; 2013.