Even if efforts for non-sputum-based TB diagnostic and prognostic biomarkers, there was limited data on blood-based immunological biomarkers among smear-negative PTB patients.Therefore, we assessed the phenotypic profile (HLA-DR, CD-38, Ki-67) of M. tuberculosis specific CD4 + T cells expressing dual IFN-γ and TNF-α cytokines from smear negative PTB patients in Addis Ababa, Ethiopia. This evidence concerns the gene IFNG and tuberculosis.