Setting: Public human immunodeficiency virus (HIV) clinic and tuberculosis (TB) clinics in Kampala, Uganda.
Objective: To examine TB-specific CD4 T-cell single and polyfunctional cytokine correlates of clinical diagnostic tests for latent tuberculous infection (LTBI) in HIV-1-infected subjects.
Design: Thirty antiretroviral therapy-naïve HIV-1-infected adults without active TB disease underwent clinical tuberculin skin test (TST), interferon-gamma release assay (IGRA), and in vitro flow cytometry analysis on cells stimulated with purified protein derivative (PPD) and TB antigens early secreted antigenic target 6 + culture filtrate protein 10 (EC) for frequencies of interleukin (IL) 2, IL-17, interferon-gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) expressing cells.
Results: PPD-specific CD4 T-cell expression of TNF-α and IFN-γ was higher in the TST-positive than in the TST-negative group. EC-specific CD4 T-cell expression of TNF-α and IL-2 was higher in the TST+ group than in the TST- group. Expression of both PPD and EC-specific expression of IL-2, IFN-γ and TNF-α were greater in IGRA-positive than in IGRA-negative subjects. The TST+ group exhibited greater polyfunctionality than the TST- group. All cytokine combinations that contained TNF-α correlated strongly with TST size.
Conclusion: While IL-2, IFN-γ and TNF-α correlate with clinical tests of LTBI, TNF-α is the dominant cytokine correlating with both TST size and magnitude of IGRA response.