CD4+CD25+/hiCD127lo Phenotype Does Not Accurately Identify Regulatory T Cells in All Populations of HIV-Infected Persons

The most commonly used regulatory T cell (Treg) phenotypes, CD4(+)CD25(hi)CD127(lo) and CD4(+)CD25(hi)FoxP3(+), were simultaneously used to determine the Treg frequency in 2 different groups of human immunodeficiency virus (HIV)-infected persons, one viremic and other aviremic. As expected, a strong correlation between both Treg phenotypes was observed in the aviremic group (r = 0.913; P < .001), but surprisingly, this correlation was completely absent in the viremic group (r = 0.143; P = .572). Data on T cell activation levels of both HIV groups suggest that the CD4(+)CD25(hi)CD127(lo) phenotype could just be mirroring the elevated numbers of activated non-regulatory T cells in the viremic HIV group.