CD4(+)CD25(+/hi)CD127(lo) 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.

Increased regulatory T cell counts in HIV-infected nonresponders to hepatitis B virus vaccine.

Hepatitis B virus (HBV) coinfection is a main cause of liver-related mortality in human immunodeficiency virus (HIV)-infected subjects. Unfortunately, HIV-infected subjects show a low rate of response to standard HBV vaccination (23%-56%), in contrast to rates >90% found in the general population, and the underlying causes (particularly cellular and molecular causes) are still unknown. We hypothesized that an increased frequency of regulatory T (T(reg)) cells could be involved in the low rate of seroconversion in HIV-infected subjects. Forty HIV-infected subjects were enrolled in the Assistance Vaccination Program against HBV of the Infectious Diseases Service from the Virgen del Rocío University Hospital, Seville, Spain. Freshly isolated peripheral blood mononuclear cells from baseline were immunophenotyped for T(reg) cells, CD4, and CD8 T cells in both naive and memory subpopulations and activation degree, as well as recent thymic emigrants. Baseline T(reg) cell frequency was found independently associated with the final nonresponse to HBV vaccine in HIV-infected subjects. Furthermore, a negative correlation between baseline frequency of T(reg) cells and antibody titers in the final response was found. These findings suggest an active role played by T(reg) cells on the immunization antigen-specific T and/or B cell responses with the final consequence of a B cell anti-HBs lower production.