The concentration of IFN-γ released in QFN-G-IT and the number of responder ESAT-6 and CFP-10 specific T cells detected by T-SPOT.TB was not correlated with number of circulating CD4 T cells (Spearman's rho [SR] = 0.221, p = 0.056; SR = 0.028, p = 0.813 and SR = 0.013, p = 0.910, respectively), as shown in Figure 3. This evidence concerns the gene CD4 and tuberculosis.