Down-Regulation of Interleukin-7 Receptor (CD127) in HIV Infection Is Associated with T Cell Activation and Is a Main Factor Influencing Restoration of CD4+ Cells after Antiretroviral Therapy

Background. Factors influencing the depletion of CD4(+) cells and the restoration of CD4(+) cells after antiretroviral therapy are not completely understood. Recently, attention has been paid to interleukin (IL)-7 and its receptor (CD127). We analyzed the influence of T cell activation and of suppression of viremia with antiretroviral therapy on this system, as well as its role in CD4(+) cell restoration after long-term antiretroviral therapy. Methods. IL-7 levels and CD127 expression on several subsets of CD4(+) and CD8(+) T lymphocytes and the activation status (CD38) of these cells were examined at baseline and during 24 months of complete viral suppression under highly active antiretroviral therapy ( HAART). Results. A total of 42 individuals with human immunodeficiency virus (HIV) infection and 10 age-matched, uninfected control subjects were examined. Before HAART, IL-7 levels were increased and CD127 expression was decreased. Down-regulation of CD127 was mainly associated with T cell activation and reverted only partially after suppression of detectable plasma HIV RNA with HAART. In a multivariate analysis, CD127 expression on CD8(+) T cells was the main determinant of the extent of CD4(+) cell gains after after successful HAART. Conclusions. The IL-7-CD127 system is impaired in HIV-infected patients. CD127 down-regulation is associated with T cell activation and with CD4(+) cell restoration after HAART