HLA-DRB1*09:01 allele is associated with anti-E immunization in a Chinese population

BACKGROUNDAnti-E is the most common and important RBC alloantibody in the Chinese population. Several studies have demonstrated that the production of specific RBC alloantibodies is associated with HLA-DRB1 polymorphisms. Considering that the Chinese population has its own unique characteristics of HLA-DRB1 polymorphisms, we investigate whether specific HLA-DRB1 alleles are associated with E immunization in a Chinese population. STUDY DESIGN AND METHODSThe frequencies of HLA-DRB1 phenotypes were compared among 78 patients possessing anti-E and 192 healthy blood donors. HLA-DRB1 genotyping was carried out using sequence-based typing method. The TEPITOPEpan software was used to predict E antigen-derived anchor peptides binding to HLA-DRB1 molecules. RESULTSThe frequency of HLA-DRB1*09:01 phenotype was significantly higher in the patients with anti-E than in healthy controls: 76.9% versus 27.6% (odds ratio, 8.7; 95% confidence interval, 4.7-16.2; corrected p value<0.0034). One E antigen-derived anchor peptide (217WMFWPSVNS225) was predicted to bind three HLA-DRB1 molecules (HLA-DRB1*04:05, *04:17, and *13:02); however, no anchor peptide was predicted to bind HLA-DRB1*09:01. CONCLUSIONThis study indicated that HLA-DRB1*09:01 phenotype was significantly more prevalent in E-immunized patients than the control group. It suggested that HLA-DRB1*09:01 molecule might represent a susceptibility phenotype enhancing formation of anti-E alloantibody. Further study would be necessary to identify the anchor peptide responsible for E alloimmunization by stimulation of specific T cells by peptide originating from E antigen.