Ekspression of Mycobacterium tuberculosis proteins ESAT-6 and CFP-10 and measurement of IFN-γ and IL-10 cytokine responses at different patient groups

IFN-? tests as an alternative to tuberculin skin test, for the diagnosis of latent tuberculosis disease. IFN-? levels synthesized by T lymphocytes which are accessory in high proportion against the antigenic stimulations are measured. It was established that the sensitivity and specificity of the IFN-? tests in which concomitantly used with M. tuberculosis-specific ESAT-6 and CFP-10 synthesized by RD1 operon was higher compared to the tuberculin skin test. In addition, the false positivity rates related with BCG vaccination and previous nontuberculous mycobacterial infections were lower in these tests. Although better results were obtained in the diagnosis of latent tuberculosis disease compared to tuberculin skin test, the sensitivity and specificity of the IFN-? tests decreased in immunosuppressed individuals, children, cases with extra-pulmonary tuberculosis and endemic places for the tuberculosis disease. Application area of the test may remain limited with the diagnosis of latent tuberculosis disease due to the variety of IFN-? response related to patient clinic; hence this test is not used widely particularly in regions where tuberculosis disease is endemic. In this study M. tuberculosis-specific ESAT-6 and CFP-10 proteins were cloned and were expressed in M15 Esherichia coli strain. These proteins were purified by using Ni-NTA agarose affinity chromatography technique. IFN-? and IL-10 responses and ?IFN-? / ?IL-10 rates were obtained occurring in different patient groups against ESAT-6 and CFP-10 proteins. The results of 78 patients referred as a group including the patients with fibronodular lesions, pleural effusion, cavity lesions, multiple cavity lesions, miliary involvement, recurrent tuberculosis, and recovered tuberculosis disease were compared with healthy control group consists of 34 person. These results were also compared with a second control group after the exclusion of 10 patient whose IFN-? responses were high, according to the tuberculosis disease prevalence in our country. It was obtained that the ?IFN-? and ?IL-10 responses and ?IFN-? / ?IL-10 rates were concordant with the clinical, radiological and laboratory findings having the prognostic value. In addition to the IFN-? tests, it was also established that the measurement of a cytokine, the indicator of such IL-10 humoral or regulator response, determination of ?IFN-? / ?IL-10 rates reflecting the immune response status against the tuberculosis bacillus increased the sensitivity and specificity.