Characterization of glycoprotein IIb/IIIa-specific alloantibodies induced by cross-strain platelet immunization in mice

Transfusion. 2021 Apr;61(4):1278-1285. doi: 10.1111/trf.16275. Epub 2021 Jan 22.

Abstract

Background: We previously described a mouse model in which platelet immunization between selected strains leads to production of alloantibodies and severe autoimmune thrombocytopenia and mimics the human condition posttransfusion purpura (PTP). This report describes studies defining epitopes recognized by these alloantibodies.

Study design: Hybridomas were produced from spleen cells of immunized mice. Glycoprotein (GP) targets of resulting monoclonal antibodies were characterized by immunoprecipitation using platelets from the immunizing strains. Antigens defined by single amino acid (AA) polymorphisms recognized by monoclonal antibodies were identified by mutagenizing target glycoproteins expressed in Chinese hamster ovary cells and observing the effects on antibody binding.

Results: Three monoclonal antibodies (417.1, 417.3, 425.1) were produced that recognized GPIIb on immunizing platelets. Monoclonal antibodies 417.1 and 417.3 both required G111 and 425.1 required V37, located on the beta propeller domain of GPIIb, for binding to platelets from the immunizing strains C57 and PWK, respectively. Injection of 417.3 and 425.1 into mice caused platelet destruction only in mice with GPIIb containing the targeted AAs.

Conclusions: Findings made provide evidence that alloantibodies produced by mice experiencing thrombocytopenia in a mouse model of PTP are specific for single AA polymorphisms that differ in GPIIb/IIIa integrin of the immunizing and immunized strains and therefore closely resemble the potent alloantibodies found in patients with PTP. The observations show that naturally occurring single AA differences in GPIIb/IIIa integrin of various mouse strains are highly immunogenic in the mouse strains studied and readily induce antibodies comparable to human platelet antigen-specific antibodies found in transfused and pregnant humans.

Keywords: FNAIT; PTP; alloantibody; platelet antigen; platelet refractoriness.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Antibodies, Monoclonal / immunology
  • Antigens / metabolism
  • Blood Platelets / immunology*
  • Blood Platelets / metabolism
  • CHO Cells / immunology
  • CHO Cells / metabolism
  • Cricetulus
  • Epitopes / immunology
  • Female
  • Hybridomas / immunology*
  • Hybridomas / metabolism
  • Immunization / adverse effects
  • Immunization / methods
  • Integrin beta3 / immunology*
  • Integrin beta3 / metabolism
  • Isoantibodies / immunology*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Models, Animal
  • Platelet Membrane Glycoprotein IIb / immunology*
  • Platelet Membrane Glycoprotein IIb / metabolism
  • Purpura, Thrombocytopenic, Idiopathic / immunology
  • Thrombocytopenia / immunology
  • Thrombocytopenia / metabolism
  • Transfusion Reaction / immunology
  • Transfusion Reaction / metabolism

Substances

  • Antibodies, Monoclonal
  • Antigens
  • Epitopes
  • Integrin beta3
  • Isoantibodies
  • Platelet Membrane Glycoprotein IIb