Persistent human immunodeficiency virus-1 antigenaemia affects the expression of interleukin-7Rα on central and effector memory CD4 ⁺ and CD8⁺ T cell subsets

Interleukin (IL)-7 and its receptor (IL-7Rα) play important roles in regulating lymphopoiesis. Previous studies have reported that human immunodeficiency virus-1 (HIV-1) viraemia affects the expression of IL-7Rα, but its effects on CD4⁺ and CD8⁺ T cell memory subsets have not been studied. Using eight-colour flow cytometry, we compared the immunophenotypic patterns of CD4⁺ and CD8⁺ T cell subsets expressing IL-7Rα and activation markers, as well as circulating IL-7 levels, in three well-defined groups of HIV-1-infected subjects: successfully treated, viraemic and long-term non-progressor (LTNP). Compared with successfully treated and LTNP subjects, viraemic patients had reduced expression of IL-7Rα on both CD4⁺ and CD8⁺ T cells, particularly on central and effector memory T cell compartments, and substantially elevated expression of activation markers on CD8⁺ T cell subsets. Circulating IL-7 levels were correlated negatively with the number of CD4⁺ and CD8⁺ T cell subsets expressing IL-7Rα; these associations were stronger with CD4⁺ T cell subsets and mainly with central and effector memory cells. The expression of activation markers on CD4⁺ and CD8⁺ cell T subsets was not related to circulating IL-7 levels. A strong negative correlation was observed between central memory CD4⁺ or CD8⁺ T cells expressing IL-7Rα and those expressing activation markers, independently of IL-7 levels. Collectively, these results provide further insight on the role of unsuppressed viral load in disrupting the IL-7/IL-7Rα system and contributing to HIV-1 disease progression.