Anti-"Mi(a)" immunization is associated with HLA-DRB1*0901.
BACKGROUND
Anti-"Mi(a)" is one of the most important irregular red blood cell antibodies found in Taiwan. The aim of this study was to investigate whether specific HLA-DRB1 alleles are associated with anti-"Mi(a)" production.


METHODS
A case-control retrospective study was performed on 68 patients showing presence of anti-"Mi(a)" and 219 unrelated control subjects from the Mackay Memorial Hospital. HLA-DRB1 genotyping was carried out using sequence-based typing method. Fisher's exact test using 2 x 2 contingency tables was used to analyze significance of the association between DRB1 polymorphisms and presence of anti-"Mi(a)" in patients.


RESULTS
HLA-DRB1*0901 allele frequency in the anti-"Mi(a)" group (30%) was significantly higher than in the control group (16%) with an odds ratio of 2.27 (95% confidence interval, 1.44-3.55; p = 0.0005; p(c) = 0.016).


CONCLUSIONS
HLA-DRB1*0901 is significantly more prevalent in the anti-"Mi(a)" patients group than in the control group. It is suggested that cells from DR9 individuals might present processed "Mi(a)" antigen-allospecific peptides more effectively than cells from individuals carrying other DR phenotypes. Finally, it was predicted that two epitopes, derived from the MiIII glycophorin amino acid sequence, were likely to bind preferentially with the DR9 molecule. Further work will be necessary to determine if these epitopes are responsible for anti-"Mi(a)" alloimmunization.
Chu
Chen-Chung
CC
Transfusion Medicine Laboratory, Medical Research Department, Mackay Memorial Hospital, Taipei, Taiwan.
Ho
Hsin-Tsung
HT
Lee
Hui-Lin
HL
Chan
Yung-Shiu
YS
Chang
Fong-Juan
FJ
Wang
Chang-Ling
CL
Lin
Marie
M
D000375:Aging; D000483:Alleles; D000595:Amino Acid Sequence; D000906:Antibodies / Q000276:immunology*; D001803:Blood Transfusion; D004912:Erythrocytes / Q000276:immunology*; D005260:Female; D006021:Glycophorins / Q000276:immunology; D006684:HLA-DR Antigens / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D059811:HLA-DRB1 Chains; D006801:Humans; D007114:Immunization; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010641:Phenotype; D016415:Sequence Alignment; D012727:Sex Characteristics; D013624:Taiwan
D000906:Antibodies; D006021:Glycophorins; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains