Phenotypic Characterization of HIV-Specific CD8+ T Cells during Early and Chronic Infant HIV-1 Infection

Although CD8+ T cells play an important role in the containment of adult HIV-1 replication, their role in infant HIV-1 infection is not as well understood. Impaired HIV-specific CD8+ T cell responses may underlie the persistently high viral loads observed in infants. We examined the frequency and phenotype of infant HIV-specific CD8+ T cells in 7 HIV-infected antiretroviral therapy-naı̈ve infants during the first 2 years of life, using class I HLA tetramers and IFN-c-ELISPOT. The frequency (0.088–3.9 % of CD3+CD8+ cells) and phenotype (CD27+CD282, CD45RA+/2, CD57+/2, HLA-DR+, CD95+) of infant HIV-specific CD8+ T cells were similar to reports in adults undergoing early infection. Unlike adults, at 23–24 months post-infection a high frequency of HIV-specific CD8+ T cells expressed HLA-DR (mean 80%, range 68–85%) and CD95 (mean 88%, range 79–96%), suggesting sustained activation and vulnerability to apoptosis. Despite comparable expansion of HIV-specific CD8+ T cells of a similar phenotype to adults during early infection, infant T cells failed to contain HIV-1 replication