Role of HLA-B51 and HLA-B52 in susceptibility to pulmonary tuberculosis.

MHC class I-restricted CD8+ T cells are important for the generation of protective immune responses in MTB infection. CD8+ CTL (cytotoxic T-lymphocyte)-derived IFN-g may be especially important both for cells lacking MHC class II molecules, e.g. in the lung and for macrophages where mycobacteria can evade recognition during chronic infection by sequestering their antigens away from sensitized CD4+ T cells. This study was designed to detect any association of MHC class I (HLA-B) molecules with pulmonary tuberculosis. A total of 75 individuals, comprising of 33 patients with pulmonary tuberculosis; 12 HIV patients who developed tuberculosis and 30 healthy controls, were included in the study. They were typed for HLA-B by the PCR-SSP method. The results of only HLA-B alleles, which are highly significant, are presented here. The number of healthy individuals with HLA-B52 was significantly high when compared to the patient groups (healthy versus TB: 21.2% versus 0.0%, OR=0.0, P<0.0001, P(c)=0.003; healthy versus HIV-TB: 21.2% versus 16.7%; OR=0.74; P<0.001; P(c)=0.003). In contrast, the number of patients, both TB- and HIV-TB-positive, with HLA-B51 was significantly high when compared to the healthy group of individuals (TB versus healthy: 36.7% versus 3%; OR=18.53; P<0.0001; P(c)=0.001; HIV-TB versus healthy: 41.7% versus 3%; OR=22.86; P<0.0001; P(c)=0.001). Only one healthy control was positive to HLA-B51; however this individual also had HLA-B52. The results of this study suggest that HLA-B52(5) has a negative, i.e. a protective association and HLA-B51(5) has a positive (susceptible) association, for pulmonary tuberculosis. Studies on HLA-B51 and HLA-B52 in a larger population to assess their role in tuberculosis may be useful for TB-vaccination strategies, since HLA profiles are likely to be related to vaccine efficacy.