Leprosy is a chronic, infectious disease, caused by Mycobacterium leprae
, Mycobacterium lepromatosis
or both, which affects the peripheral nervous system and the skin. Activation of cellular immunity in infected individuals depends on antigen recognition, which involves relevant HLA-Class II alleles. Therefore, the objective of this study was to determine HLA-Class II allele frequencies (HLA-DRB1and-DQB1)in Mexican Mestizo leprosy patients and compare themwith healthy controls, in order to define their role in the genetic susceptibility to this infection.The genomic DNA of each participant was obtained from peripheral blood, using the salting-out method. PCR amplification and hybridization ofHLA-class II alleleswas made by PCR-SSO. The results showed that frequencies of HLA-DRB1*15(Pc
=0.003, OR=3.3 95%CI=1.53-7.33), HLA-DQB1*05(Pc =0.00003, OR=6.03 95%CI=2.49-14.61) and HLA-DQB1*06 (Pc
=0.007, OR=2.89, 95%CI=1.38-6.04)were significantly higher among leprosypatients than those of healthy controls. The study suggests that HLA-DRB1*15, HLA-DQB1*05, and HLA-DQB1*06 are associated with leprosy susceptibility in the Mexican Mestizo population.