because hla-b27 , though significantly more common in flax byssinosis , is not necessary for its occurrence ( 77.5 % of our patients did not have it ) , it is possible that the increase in the frequency of hla-b27 is attributable to an association with other genes , perhaps those regulating the immune response or coding for antigens at other hla loci .
C0301872
immune response
C0003320
antigens