Impaired IFN-γ-secreting capacity in mycobacterial antigen-specific CD4 T cells during chronic HIV-1 infection despite long-term HAART

Abstract

To determine whether long-term HAART in chronic HIV-1 infection restores fully functional Mycobacterium tuberculosis (MTB)-specific CD4 T-cell responses. A cross-sectional study of HIV-1-seropositive subjects on continuous HAART for over one year with CD4 cell counts greater than 300 cells/μl and undetectable viraemia, antiretroviral-naive individuals with primary HIV-1 infection (PHI), and healthy bacillus Calmette–Guérin-vaccinated low-risk controls. Purified protein derivative (PPD)-specific cytokine-secreting CD4 T cells were quantified ex vivo by enzyme-linked immunospot assay and intracellular cytokine staining. Lymphoproliferation was detected by [3H]-thymidine incorporation. PPD-specific IFN-γ-secreting CD4 T cells were markedly reduced in chronic HAART-treated HIV-1-positive and PHI subjects compared with healthy controls [medians 30, 155 and 582 spot-forming cells/million peripheral blood mononuclear cells (PBMC), respectively, P Conclusion: Despite an improvement in CD4 T-cell counts after HAART, MTB-specific CD4 T cells from chronically infected patients have impaired IFN-γ-secreting capacity. The early initiation of HAART might preserve functional CD4 T-cell responses to MTB, and warrants evaluation in populations with a high risk of dual infection.