In particular, some studies reported an association of polyfunctional TNF-α+IFN-γ+IL-2+ lymphocytes with protective immunity to TB and the persistence of latency (28, 29) and found increased proportions of monofunctional TNF-α+ or bifunctional TNF-α+IFN-γ+ CD4+ T cells in subjects with active TB (28–31). This evidence concerns the gene IFNG and tuberculosis.