Identification of a human heavy chain antibody fragment directed against human platelet alloantigen 1a by phage display library

N. Okamoto, S. D. Kennedy, E. A. Barron-Casella, J. F. Casella, H. Inoko, T. S. Kickler

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The human platelet alloantigen HPA-1a (Pl(A1)) is responsible for most cases of post-transfusion purpura and neonatal alloimmune thrombocytopenia in the Caucasian population. HPA-1a and HPA-1b are two allelic forms of the platelet membrane glycoprotein IIIa (GPIIIa) gene that differ by a single amino acid. In this report, we describe the development of a recombinant heavy chain antibody fragment capable of distinguishing between the homozygous forms of HPA-1a and HPA-1b. This antibody fragment was isolated from the lymphocytes of an immunized individual through the use of a phage display library system. The recombinant antibody fragment reacted with human platelet lysates from HPA-1a homozygous donors, the HPA-1a form of recombinant N-terminal GPIIIa and intact HPA-1a platelets, but did not react with platelet lysate from HPA-1b homozygous donors, reduced HPA-1a form of platelet GPIIIa or other platelet glycoproteins. This HPA-1a specific human antibody fragment works well in common laboratory assays such as ELISA and flow cytometry, which can assist in identifying HPA-1b homozygous individuals who are known to have a higher risk for developing neonatal alloimmmune thrombocytopenia and post-transfusion purpura. Thus, selection of recombinant antibody fragment using phage display offers a promising alternative to hybridoma technology for the production of human antibodies against human alloantigens and holds potential as a technique in therapeutic applications.

Original languageEnglish (US)
Pages (from-to)156-163
Number of pages8
JournalTissue Antigens
Issue number2
StatePublished - 1998


  • Glycoprotein IIIa human platelet alloantigen
  • Phage display library
  • Recombinant antibody

ASJC Scopus subject areas

  • Genetics
  • Biochemistry
  • Immunology and Allergy
  • Immunology


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