Interferon-γ release assay in HIV-infected patients with active tuberculosis: impact of antituberculous drugs on host immune response.

The objective of the study was to: 1) investigate the performance of QuantiFERON-TB Gold In-Tube (QFT-GIT) in HIV-infected patients with active tuberculosis (TB); 2) evaluate the sequential changes in QFT-GIT assay during the treatment response; 3) investigate the direct in vitro effects of antituberculous drugs on both secretion of IFN-gamma and apoptosis of T cells. Forty-four HIV-patients with active TB were enrolled and tested with QFT-GIT. Thirteen of them were followed longitudinally by QFT-GIT, performed at baseline and six and nine months after TB-treatment onset. For in vitro experiments, cells from healthy donors and HIV-naive subjects were pretreated with four antituberculous-drugs, and then examined for IFN-gamma secretion and apoptosis of T-cells. The QFT-GIT was positive in 66%, negative in 11.3% and indeterminate in 22.7%. Longitudinal analysis in 13 HIV-TB subjects showed that at therapy completion a reversion to negative response was found only in 38.4% of patients, but in 30.7% the QFT-GIT remained positive. Overall, during the anti-TB treatment no significant decrease in average IFN-gamma response was observed in these patients (p