In addition, a study demonstrated that the frequency of purified protein derivate-specific CD4 T cells secreting TNF-α but not IFN-γ or IL-2 with a differentiated effector memory phenotype (CD45RA−CCR7−CD127−, TNF-α-only TEFF) was able to distinguish between active TB from LTBI and correlate with a risk factor for progression (108). This evidence concerns the gene IL2 and tuberculosis.