HLA-DRB1 and tuberculosis: HLA-DRB1*0701 genotype significantly affected TB-Ag specific IFN-γ response (TBAg-Nil) (P<0.001): The IFN-γ values in patients with two HLA-DRB1*0701 alleles (homozygous for HLA-DRB1*0701) were significantly lower than those in patients with one HLA-DRB1*0701 allele (heterozygous for HLA-DRB1*0701) (0.15 IU/ml [IQR, 0.06–0.26] vs 1.91 IU/ml [IQR, 0.65–4.21], P = 0.008).