Evaluation of ifn- γ response to cfp-10 and esat-6 antigens by elispot test in tuberculosis

There has been considerable interest in evaluating IFN-γ responses to, Mycobacterium tuberculosis specific, CFP-10 and ESAT-6 antigens for discriminating latent infection and BCG effect from tuberculosis disease. We aimed to evaluate the feasibility of determination of IFN-γ responses to CFP-10 and ESAT-6 antigens for differentiation of active tuberculosis infection from latent tuberculosis infection or BCG effect. Changes in IFN-γ responses during the treatment of active TB disease were also observed. ELISPOT test was applied to 84 active tuberculosis patients, 104 contacts, 71 suspect patients and 68 healthy controls. Peripheral blood mononuclear cells were stimulated by Mycobacterium tuberculosis antigens (PPD, ESAT-6 and CFP-10). IFN-γ responses were measured and evaluated according to the criteria... described by Lalvani A et al. All groups were followed up for clinical and radiologic signs, as well as Mycobacterium tuberculosis smear and culture results. IFN-γ responses were significantly higher in active TB patients compared to healthy donors and suspect patients.(p<0,01) ESAT-6 had the highest positive response rate in TB and culture confirmed tuberculosis group. When TB household contacts and healthy controls were compared, CFP-10 and ESAT-6 seemed to be more useful than TST in TB contacts for displaying LTB. Although CFP-10 spot numbers were much more than ESAT-6 spots at the beginning and follow up period, statistically there was no difference in terms of median values.(P: 0,069) Both ESAT-6 and CFP-10 spots were prone to decline during the follow up period. Testing INF-γ responses to CFP-10 by ELISPOT might be useful in the diagnosis of latent and active tuberculosis disease and much more helpful for discriminating latent tuberculosis infection from BCG effect.