Specific patterns of CD4-associated immunosenescence in vertically HIV-infected subjects

Vertical transmission of human immunodeficiency virus (HIV) represents an important world-wide health problem although the incidence in developed countries has been drastically reduced by the extensive use of highly active antiretroviral therapy. Vertically HIV-infected subjects have been exposed to the virus during the maturation of their immune systems and have suffered a persistent chronic activation throughout their lifetime; the consequences of this situation for their immune system are not fully understood. The objective of this study was to analyse immunosenescence-related parameters in different CD4 T-cell subsets. Fifty-seven vertically HIV-infected subjects and 32 age-matched healthy subjects were studied. Activation (HLA– DR+), senescence (CD28– CD57+) and proliferation (Ki67+) were analysed on different CD4 T-cell subsets: naive (CD45RA+ CD27+), memory (CD45RO+ CD27+), effector memory (CD45RO+ CD27–) and effector memory RA (CD45RA+ CD27–). Compared with healthy subjects, vertically HIV-infected subjects showed increased naive and memory CD4 T-cell frequencies (p 0.035 and p 0.010, respectively) but similar frequencies of both effector subsets. Whereas naive CD4 T cells were not further altered, memory CD4 T cells presented increased levels of senescence and proliferation markers (p <0.001), effector memory CD4 T cells presented increased levels of activation, senescence and proliferation markers (p <0.001) and effector memory RA CD4 T cells presented increased levels of activation and senescence (p <0.001) compared with healthy subjects. Despite long periods of infection, vertically HIV-infected subjects show specific patterns of immunosenescence, revealing a preserved CD4 T-cell homeostasis for subset differentiation and distribution. Nevertheless, excepting the naive subpopulation, all subsets experienced some immunosenescence, pointing to uncertain consequences of the future aging process in these subjects.