Factors Associated With In Vitro Interferon-gamma Production in Tuberculosis

Background/Purpose: Macrophage activation assisted by interferon-gamma (IFN-gamma) is a primary mechanism by which Mycobacterium tuberculosis is killed, but IFN-gamma production is inhibited in tuberculosis (TB) patients. The production of IFN-gamma is influenced by many factors, such as interleukin (IL)-10, IL-12, IL-18, and clinical diseases; but the relative importance of each factor is unclear. Methods: We evaluated the effects of these factors in 46 healthy individuals, 81 patients with TB, and 88 patients with non-TB pneumonia. The responses of IFN-gamma, IL-10, IL-12 and IL-18 were determined from phytohemagglutinin-stimulated peripheral blood mononuclear cells (PBMCs). Results: General linear model analysis showed that disease status and IL-12 response were the independent factors associated with the IFN-gamma response. The production of IFN-gamma was not affected by IL-10 and IL-18. There was a significant relationship between the IFN-gamma response and the IL-12 response among patients with non-TB pneumonia, patients with TB, and healthy participants (Pearson's correlation coefficients of 0.466, 0.483, and 0.464, respectively). Conclusion: Production of IFN-gamma in PBMCs was associated with active pulmonary TB and IL-12 response.