Immunogenetics of episcleritis in leprosy.

Human leukocyte antigens (HLA) were analyzed among Japanese leprosy patients to identify any possible determinants in the development of episcleritis in leprosy patients. Seventy-nine Japanese leprosy patients (33 patients with history of episcleritis and 46 patients without episcleritis) and 114 healthy control subjects were investigated. Human leukocyte antigen-class I and class II specificities were determined serologically by the standard microcytotoxicity test. The HLA-DRB1, -DRB5, -DQA1, and -DQB1 genotypings were performed by using the polymerase chain reaction (PCR)-single strand conformation polymorphism and PCR-restriction fragment length polymorphism analyses. The frequency of HLA-Cw3 was significantly increased among the patients with episcleritis (66.7%) compared to patients without episcleritis (43.5%; odds ratio = 2.6, P < 0.05). The frequency of HLA-DR4 was significantly decreased among the patients with episcleritis (15.2%) compared to patients without episcleritis (39.1%; odds ratio = 0.28, P < 0.05) and the controls (46.5%; odds ratio = 0.21, P < 0.001). At the genomic level, frequencies of the HLA-DRB1*0405, -DQB1*0401, and -DQB1*0302 alleles were significantly decreased among the patients with episcleritis (0%, 0%, and 6.1%, respectively) compared to patients without episcleritis (15.2%, 13.0%, and 26.1%, respectively; odds ratio = 0.07, 0.09, and 0.18, P < 0.05). HLA-DRB1*0405 and -DQB1*0401 were also significantly decreased among the patients with episcleritis compared to the controls (29.8% and 29.8%; odds ratio = 0.04, P < 0.0001). Our results suggest that HLA-Cw3 antigen confers the susceptibility to the development of episcleritis among Japanese leprosy patients. Concurrently, the DRB1 (the -DBR1*0405), and/or DQB1 (the -DQB1*0401 and -DQB1*0302) alleles might provide protection against leprous episcleritis.