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

Background Only a small proportion of subjects exposed to isocyanates devel op occupational asthma, suggesting individual predisposition. The human leu cocyte antigen (HLA) class II molecules may play a crucial role in the deve lopment of the immune response to isocyanates. Objectives To investigate the role of HLA class II molecules in the develop ment of toluene diisocyanate (TDI)-induced asthma. Subjects Sixty-seven asthmatic subjects and 27 asymptomatic exposed subject s (controls) were typed at the HLA class II DQA1, DQB1 and DRB1 loci by pol ymerase chain reaction (PCR)-based techniques. Results The frequencies of DQA1*0104 and DQB1*0503 were significantly incre ased in asthmatics compared with asymptomatic exposed subjects, while DQA1* 0101 and DQB1*0501 were significantly increased in asymptomatic exposed sub jects. No significant difference was found in the distribution of DRB1 alle les between asthmatics and controls. Conclusions The results of this study indicate that HLA-regulated immune me chanisms are involved in TDI-induced asthma and that, in exposed subjects, specific factors may increase or decrease the risk of developing disease.