Possible presence of enhancing antibodies in idiopathic thrombocytopenic purpura

Yi Yuan Yang, Peter Fischer, Sy Jye Leu, Min Zhu, Virgil L. Woods, Pojen P. Chen

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

It is difficult to detect IgG anti-platelet autoantibodies in idiopathic thrombocytopenic purpura (ITP). Recently, it was reported that reactivity with glycoprotein IIb/IIIa was lost when IgG anti-GPIIb/IIIa antibodies from seven ITP patients were digested with pepsin to yield F(ab')2 fragments. These findings suggested that some IgG antiplatelet autoantibodies in ITP may be of low affinity and thus require the presence of 'enhancing' anti-IgG antibodies (i.e. rheumatoid factors, RFs) for detection. To test this hypothesis, we used a phage display technique to isolate five IgG RFs from an ITP patient (patient 1). Sequence analysis revealed that these RFs consisted of two clones, represented by GG3 and GG48. Both representative RFs bound specifically to IgG Fc fragments with apparent dissociation constants of 8.2x10-8 M and 8.8x10-7 M, respectively. Moreover, IgG RFs were subsequently found in a serum sample from patient 1. Combined, these results suggest that IgG RFs may occur in ITP, and may be required for the detection of some IgG anti-platelet autoantibodies and for the corresponding antibody- mediated platelet destruction in autoimmune ITP.

Original languageEnglish
Pages (from-to)69-80
Number of pages12
JournalBritish Journal of Haematology
Volume104
Issue number1
DOIs
Publication statusPublished - 1999

Keywords

  • Antiplatelet autoantibody
  • Combinatorial library
  • Enhancing antibody
  • ITP
  • Rheumatoid factor

ASJC Scopus subject areas

  • Hematology

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