Cytokine responses induced by Mycobacterium tuberculosis in patients with HIV-1 infection and tuberculosis

Objective: Tuberculosis (TB) is an important opportunistic infection in HIV patients. Immune responses to Mycobacterium tuberculosis in HIV/TB patients were evaluated. Methods: Fifteen patients with HIV/TB, ten with HIV, four with TB, and five controls were enrolled. Peripheral blood mononuclear cells were isolated and stimulated with mycobacterial antigen (PPD). Interferon (IFN)-γ and TNF-α in culture supernatants were measured by ELISA. Results: IFN-γ and TNF-α production after PPD stimulation was markedly decreased in HIV patients, but not in HIV/TB patients. In HIV patients with a CD4 cell count of less than 200/mm³, IFN-γ and TNF-α production after PPD stimulation was higher in HIV/TB patients than in HIV patients. Cytokine responses to M. tuberculosis reconstituted after highly active antiretroviral therapy (HAART) and were prominent in HIV/TB patients. Conclusions: Cytokine responses to M. tuberculosis were retained in HIV-infected patients with tuberculosis, even in patients with a CD4 cell count of less than 200/mm³, and reconstituted after HAART.