Distribution of DRB1 and DQB1 HLA class II alleles in occupational asthma due to western red cedar

Occupational asthma caused by western red cedar is a common problem in sawm ill industries. The objective of this study was to examine a possible assoc iation of human leukocyte antigen (HLA) class II genetic markers with susce ptibility or resistance to western red cedar induced asthma. The distribution of DRB1 and DQB1 HLA class II alleles and DRB1-DQB1 haplot ypes was studied in 56 Caucasian patients with proven red cedar asthma and 63 healthy Caucasian control subjects exposed to red cedar dust. DRB1 and D QB1 high resolution typing was performed by the polymerase chain reaction-b ased method. Patients with red cedar asthma had a higher frequency of HLA DQB1*0603 and DQB1*0302 alleles compared to a group of healthy exposed control subjects a nd a reduced frequency of DQB1*0501 allele. The frequency of the DRB1*0401- DQB1* 0302 haplotype was increased and the DRB1*0101-DQB1*0501 haplotype wa s reduced. These findings suggest that genetic factors such as human leukocyte antigen class II antigens may be associated with susceptibility or resistance to d evelopment of red cedar asthma.