Disruption of PF4/H multimolecular complex formation with a minimally anticoagulant heparin (ODSH)

Thromb Haemost. 2012 Apr;107(4):717-25. doi: 10.1160/TH11-11-0795. Epub 2012 Feb 8.

Abstract

Recent studies have shown that ultra-large complexes (ULCs) of platelet factor 4 (PF4) and heparin (H) play an essential role in the pathogenesis of heparin-induced thrombocytopenia (HIT), an immune-mediated disorder caused by PF4/H antibodies. Because antigenic PF4/H ULCs assemble through non-specific electrostatic interactions, we reasoned that disruption of charge-based interactions can modulate the immune response to antigen. We tested a minimally anticoagulant compound (2-O, 3-O desulfated heparin, ODSH) with preserved charge to disrupt PF4/H complex formation and immunogenicity. We show that ODSH disrupts complexes when added to pre-formed PF4/H ULCs and prevents ULC formation when incubated simultaneously with PF4 and UFH. In other studies, we show that excess ODSH reduces HIT antibody (Ab) binding in immunoassays and that PF4/ODSH complexes do not cross-react with HIT Abs. When ODSH and unfractionated heparin (UFH) are mixed at equimolar concentrations, we show that there is a negligible effect on amount of protamine required for heparin neutralisation and reduced immunogenicity of PF4/UFH in the presence of ODSH. Taken together, these studies suggest that ODSH can be used concurrently with UFH to disrupt PF4/H charge interactions and provides a novel strategy to reduce antibody mediated complications in HIT.

Publication types

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

MeSH terms

  • Animals
  • Anticoagulants / pharmacology
  • Binding Sites
  • Biophysics / methods
  • Cattle
  • Dose-Response Relationship, Drug
  • Heparin / analogs & derivatives
  • Heparin / chemistry
  • Heparin / metabolism
  • Heparin / pharmacology
  • Heparin / therapeutic use*
  • Humans
  • Immunoassay / methods
  • Kinetics
  • Platelet Factor 4 / metabolism*
  • Protamines / metabolism
  • Thrombin / metabolism
  • Thrombocytopenia / metabolism

Substances

  • Anticoagulants
  • N-desulfated,2-O,3-O-desulfated heparin
  • Protamines
  • Platelet Factor 4
  • Heparin
  • Thrombin