Glycoprotein IIb/IIIa autoantigenic repertoire in chronic idiopathic thrombocytopenic purpura

Br J Haematol. 1995 Dec;91(4):971-5. doi: 10.1111/j.1365-2141.1995.tb05421.x.

Abstract

The objective of the present study was to further disclose the autoantigenic repertoire carried by the platelet glycoprotein (GP) IIb/IIIa complex. IgG-F(ab')2 fragments were prepared from two prototype ITP patients, and their ability to block the binding of GPIIb/IIIa reactive antibodies derived from other patients with ITP was evaluated using a modified MAIPA asay; a PlA1 alloantiserum and 20 normal sera were included as controls. It was found that the two prototype IgG-F(ab')2 fragments were each able to significantly block the binding of serum IgG to GPIIb/IIa in six (55%) and seven (64%) out of 11 patients with chronic ITP, respectively. No significant blocking effect was observed for IgG-F(ab')2 fragments prepared from normal subjects. Also, the binding of the PlA1 alloantiserum to its epitope on GPIIIa was not affected by any of the blocking IgG-F(ab')2 fragments exploited in the study. These data substantiate that in chronic ITP at least half of the GPIIb/IIIa reactive sera bind to homogenous autoepitopes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Antibodies, Blocking / immunology*
  • Antigen-Antibody Reactions
  • Autoantibodies / immunology*
  • Female
  • Humans
  • Immunoglobulin Fab Fragments / immunology*
  • Immunologic Techniques
  • Male
  • Middle Aged
  • Platelet Glycoprotein GPIIb-IIIa Complex / immunology*
  • Platelet Glycoprotein GPIIb-IIIa Complex / metabolism
  • Purpura, Thrombocytopenic, Idiopathic / immunology*

Substances

  • Antibodies, Blocking
  • Autoantibodies
  • Immunoglobulin Fab Fragments
  • Platelet Glycoprotein GPIIb-IIIa Complex