A possible explanation for this cytokine's increased levels after treatment is based on a study performed by Jo et al. (2003) [43], which showed that at the moment of tuberculosis diagnosis, the IFN-γ concentration is much higher at the infection site than in the peripheral blood, suggesting that during tuberculosis activity, there is a localization of specific lymphocytes against the mycobacterial antigen at the infection site and that the increase in the IFN-γ serum concentration at the chemotherapy stage coincides with the arrival of lymphocytes in the peripheral blood. This evidence concerns the gene IFNG and tuberculosis.