In tuberculosis, CTL cells might have a protective role through a variety of mechanisms - (1) IFN-γ and TNF-α are produced; (2) Mycobacterium tuberculosis antigens presented by MHC coupled to HLA-I (human leucocyte antigen-I) complex are recognized; and (3) infected cells are induced to undergo apoptosis [6,7]. Here, IFNG is linked to tuberculosis.