Pulmonary tuberculosis: evaluation of interferon-gamma levels as an immunological healing marker based on the response to the Bacillus Calmette-Guerin

Tuberculosis (TB) is a disease caused by Mycobacterium tuberculosis whose interaction with the host may lead to a cell-mediated protective immune response. The presence of interferon<FONT FACE=Symbol>-g</FONT> (IFN-gamma) is related to this response. With the purpose of understanding the immunological mechanisms involved in this protection, the lymphoproliferative response, IFN<FONT FACE=Symbol>-g</FONT> and other cytokines like interleukin (IL-5, IL-10), and tumor necrosis factor alpha (TNF<FONT FACE=Symbol>-a</FONT>) were evaluated before and after the use of anti-TB drugs on 30 patients with active TB disease, 24 healthy household contacts of active TB patients, with positive purified protein derivative (PPD) skin tests (induration > 10 mm), and 34 asymptomatic individuals with negative PPD skin test results (induration < 5 mm). The positive lymphoproliferative response among peripheral blood mononuclear cells of patients showed high levels of IFN<FONT FACE=Symbol>-g</FONT>, TNF<FONT FACE=Symbol>-a</FONT>, and IL-10. No significant levels of IL-5 were detected. After treatment with rifampicina, isoniazida, and pirazinamida, only the levels of IFN<FONT FACE=Symbol>-g</FONT> increased significantly (p < 0.01). These results highlight the need for further evaluation of IFN<FONT FACE=Symbol>-g</FONT> production as a healing prognostic of patients treated.