Association between HLA genes and susceptibility to toluene diisocyanate-induced asthma

Background: Only a small proportion of subjects exposed to isocyanates develop occupational asthma, suggesting individual predisposition. The human leucocyte antigen (HLA) class II molecules may play a crucial role in the development of the immune response to isocyanates. Objectives To investigate the role of HLA class II molecules in the development of toluene diisocyanate (TDI)-induced asthma. Subjects: Sixty-seven asthmatic subjects and 27 asymptomatic exposed subjects (controls) were typed at the HLA class II DQA1, DQB1 and DRB1 loci by polymerase chain reaction (PCR)-based techniques. Results: The frequencies of DQA1*0104 and DQB1*0503 were significantly increased in asthmatics compared with asymptomatic exposed subjects, while DQA1*0101 and DQB1*0501 were significantly increased in asymptomatic exposed subjects. No significant difference was found in the distribution of DRB 1 alleles between asthmatics and controls. Conclusions: The results of this study indicate that HLA-regulated immune mechanisms are involved in TDI- induced asthma and that, in exposed subjects, specific factors may increase or decrease the risk of developing disease.