Study of HLA class II alleles by PCR oligotyping in leprosy patients from north India.

Host factors seem to play an important role in determining the immune response and the differential manifestations of lepromatous (LL) and tuberculoid (TT) leprosy. In order to investigate the role of immunogenetic factors in determining the form of leprosy, the HLA class II alleles of DRB1, DRB3, DRB5, DQA1, DQB1 and DPB1 were studied by a PCR oligotyping technique in 93 patients and 47 healthy controls. DRB11501 and DRB11502 (two of five tested subsets of the serologically defined DR2) accounted for 81.5% of the multibacillary patients (relative risk 16.3) and 60.7% of the TT patients (relative risk 5.7) compared to 21.3% in normal, ethnically- and geographically-matched controls. The much stronger association of DRB11501 with the multibacillary form than with the TT type of leprosy suggests a possible role in the differential immune response to M. leprae antigens. DQB10601 was found significantly more often than in controls throughout the leprosy spectrum, while DQA10103 was most frequent in the LL group and DQA10102 was selectively increased in the borderline lepromatous (BL) patients. On the other hand, DRB10701, DQB10201 and DQA10201 were decreased in the multibacillary leprosy patients (MLP) compared to TT patients and controls, and DQB10503 was selectively decreased in TT patients, suggesting that these HLA alleles might play a role in modulating the immune response that determines the form of leprosy that develops in each patient.