The immune response to the HPA-1a antigen: association with HLA-DRw52a.
Antibodies to the HPA-1a antigen can elicit a condition in the new-born known as neonatal alloimmune thrombocytopenia (NAITP). Retrospective and prospective studies have shown that there is a strong correlation between the presence of HLA-DR3, HLA-DRw52 in the mother and the antibody response to HPA-1a. HLA Class II molecules play an important role in the initiation of the immune response and it has been postulated that HPA-1a antibody production could be determined by the presence of a specific HLA Class II molecule at the surface of the antigen-presenting cell. Thirty-one HPA-1a negative women with HPA-1a antibodies (responders) and nine HPA-1a negative women without HPA-1a antibodies (non-responders) were recruited. They were studied using serological HLA Class I and Class II typing and RFLP analysis with a DR beta probe. We found that all responders had the HLA-DRw52a sub-specificity confirming recently published data. Moreover, two of the nine non-responders were also found to be HLA-DRw52a. These results suggest that the HLA-DRw52a molecule is necessary for HPA-1a antibody responsiveness but not sufficient. The results also indicate that in HPA-1a negative women the absence of HLA-DRw52a is associated with a very low risk of being antibody producers and hence, is associated with a very low risk for NAITP in their new-borns.
Décary
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Blood Services, Canadian Red Cross Society, Montréal, Québec, Canada.
L'Abbé
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D
Tremblay
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Chartrand
P
P
D016824:Antigens, Human Platelet / Q000235:genetics / Q000276:immunology*; D001483:Base Sequence; D004247:DNA; D005260:Female; D006684:HLA-DR Antigens / Q000235:genetics / Q000276:immunology*; D059810:HLA-DR Serological Subtypes; D006650:Histocompatibility Testing; D006801:Humans; D039661:Integrin beta3; D008969:Molecular Sequence Data; D012150:Polymorphism, Restriction Fragment Length; D011446:Prospective Studies; D012189:Retrospective Studies
D016824:Antigens, Human Platelet; D006684:HLA-DR Antigens; D059810:HLA-DR Serological Subtypes; C051104:HLA-DR52 antigen; C061248:ITGB3 protein, human; D039661:Integrin beta3; D004247:DNA