To identify specific T cells producing IFN-γ and IL-4 in response to RD1 antigens in vitro, PBMC from TB patients and controls, cultured for 6 days in the presence of rESAT-6-CFP10 fusion protein, were harvested and stained for intracellular expression of IL-4 (N = 19, 10 had a complete set of follow up data, and 9 had only baseline and two weeks data ) and IFN-γ (N = 39, 10 had a complete set of data, 22 had baseline and two weeks, 4 had baseline, two weeks and two months, 2 had baseline and one week and 1 individual had only baseline data. This evidence concerns the gene IFNG and tuberculosis.