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This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Watkins, N. A. Articles by Ouwehand, W. H. Search for Related Content PubMed PubMed Citation Articles by Watkins, N. A. Articles by Ouwehand, W. H. Related Collections Hemostasis, Thrombosis, and Vascular Biology Transplantation Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  Blood, 1 March 2002, Vol. 99, No. 5, pp. 1833-1839 TRANSPLANTATION HPA-1a phenotype-genotype discrepancy reveals a naturally occurring Arg93Gln substitution in the platelet 3 integrin that disrupts the HPA-1a epitope Nicholas A. Watkins, Elisabeth Schaffner-Reckinger, David L. Allen, Graham J. Howkins, Nicolaas H. C. Brons, Graham A. Smith, Paul Metcalfe, Michael F. Murphy, Nelly Kieffer, and Willem H. Ouwehand From the Department of Haematology, Division of Transfusion Medicine, University of Cambridge, United Kingdom; the Laboratoire Franco-Luxembourgeois de Recherche Biomédicale, (CNRS/CRP-Santé), Luxembourg, Grand-Duchy of Luxembourg and National Blood Service East Anglia Centre, Cambridge and Oxford Centre, Oxford, United Kingdom; and the Division of Haematology, National Institute for Biological Standards and Control, Potters Bar, United Kingdom. A single nucleotide polymorphism (SNP) at position 196 in the 3 integrin causes a Leu33Pro substitution in the mature protein. Alloimmunization against the 3Leu33 form (human platelet antigen [HPA]-1a, PlA1, Zwa) in patients who are 3Pro33 homozygous (HPA-1b1b, PlA2A2, Zwbb) causes neonatal alloimmune thrombocytopenia, posttransfusion purpura, or refractoriness to platelet transfusion. Studies with recombinant proteins have demonstrated that amino acids 1 to 66 and 288 to 490 of the 3 integrin contribute to HPA-1a epitope formation. In determining the HPA-1a status of more than 6000 donors, we identified a donor with an HPA-1aweak phenotype and an HPA-1a1b genotype. The platelets from this donor had normal levels of surface IIb3 but reacted only weakly with monoclonal and polyclonal anti-HPA-1a by whole blood enzyme-linked immunosorbent assay (ELISA), flow cytometry, and sandwich ELISA. We reasoned that an alteration in the primary nucleotide sequence of the 3Leu33 allele of this donor was disrupting the HPA-1a epitope. In agreement with this hypothesis, sequencing platelet RNA-derived IIb and 3 cDNA identified a novel G/A SNP at position 376 of the 3 integrin that encodes for an Arg93Gln replacement in the 3Leu33 allele. Coexpression of the 3Leu33Gln93 encoding cDNA in Chinese hamster ovary cells with human IIb cDNA showed that the surface-expressed IIb3 reacted normally with 3 integrin-specific monoclonal antibodies but only weakly with monoclonal anti-HPA-1a. Our results show that an Arg93Gln mutation in the 3Leu33 encoding allele disrupts the HPA-1a epitope, suggesting that Arg93 contributes to the formation of the HPA-1a B-cell epitope. © 2002 by The American Society of Hematology.   CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

	Copyright © 2002 by American Society of Hematology         Online ISSN: 1528-0020