Loss of CD127 expression defines an expansion of effector CD8⁺ T cells in HIV-infected individuals

The immunodeficiency that follows HIV infection is related to the virus-mediated killing of infected CD4⁺ T cells, the chronic activation of the immune system, and the impairment of T cell production. In this study we show that in HIV-infected individuals the loss of IL-7R (CD127) expression defines the expansion of a subset of CD8⁺ T cells, specific for HIV as well as other Ags, that show phenotypic (i.e., loss of CCR7 and CD62 ligand expression with enrichment in activated and/or proliferating cells) as well as functional (i.e., production of IFN-γ, but not IL-2, decreased ex vivo proliferative potential and increased susceptibility to apoptosis) features of effector T cells. Importantly, in HIV-infected individuals the levels of CD8⁺CD127^- T cells are directly correlated with the main markers of disease progression (i.e., plasma viremia and CD4⁺ T cell depletion) as well as with the indices of overall T cell activation. In all, these results identify the expansion of CD8 ⁺CD127^- effector-like T cells as a novel feature of the HIV-associated immune perturbation. Further studies are thus warranted to determine whether measurements of CD127 expression on CD8⁺ T cells may be useful in the clinical management of HIV-infected individuals.