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Keywords:

  • PD-1;
  • CD38;
  • HLA-DR;
  • T cell subsets

Abstract

CD4+CD8+ double positive T cells represent a minor peripheral blood lymphocyte population. CD4+ expression on CD8+ T cells is induced following cellular activation, and as chronic HIV-1 infection is associated with generalized immune activation, double positive T cells studies have become necessary to understand the immunopathology of human immunodeficiency virus (HIV). The frequency of double positive T cells in persons infected with HIV was studied in comparison to uninfected controls. Further, the expression of CD38, HLA-DR, and programmed death (PD)-1 on these cells were ascertained. HIV-1 specific double positive T cells were also studied for their cytokine secretory ability and phenotype. A significantly higher double positive cell population was observed in the patients with advanced HIV disease (CD4+ T cell counts below 200 cells/µl), as compared to patients with CD4+ T cell counts above 500 cells/µl. Double positive T cells from patients with symptomatic HIV disease had a significantly increased activation and exhaustion levels, compared to asymptomatic subjects and to single positive T cells from the same subjects. HIV-1 specific double positive T cells showed further increase in CD38 and PD-1 expression levels. The proportion of CD38 and PD-1 expressing total and HIV-1 specific double positive T cells correlated positively with HIV-1 plasma viremia and negatively with CD4+ T cell counts. HIV infection results in a marked increase of double positive T cell population, and this cell population shows higher level of activation and exhaustion (increased PD-1 expression) compared to the single positive CD4+ and CD8+ T cells. J. Med. Virol. 84:845–856, 2012. © 2012 Wiley Periodicals, Inc.