Study of CD4+CD8+ Double positive T‐lymphocyte phenotype and function in Indian patients infected with HIV‐1

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.