title: Serological features of antibodies to protamine inducing thrombocytopenia and thrombosis.
abstract: BACKGROUND
  A significant proportion of patients undergoing cardiopulmonary bypass develop anti-protamine antibodies, with or without the association of thromboembolic events.
  
  
  METHODS
  We extensively investigated the serological features of protamine antibodies, which developed in six patients who were clinically suspected to have heparin-induced thrombocytopenia (HIT). Three patients had thrombotic events. Sera were tested by four different commercially available immunoassays, a heparin-platelet aggregation test, and for their binding properties to heparin, platelet factor 4 (PF4), complex heparin-PF4, protamine, and protamine complex with heparin. Sera from four patients were also tested for the capability to induce platelet activation and the formation of platelet-monocyte heterotypic aggregates.
  
  
  RESULTS
  The ELISA assay Zymutest HIA was strongly positive in all cases, the HPIA Asserachrome was borderline, and the gel centrifugation test PaDGIA was positive in two tested patients. Platelet aggregation tests were negative. Using a variation of the Zymutest HIA we demonstrate that IgG antibodies bound only to protamine or protamine complex with heparin, but not to heparin or PF4 only. Sera-induced platelet P-selectin expression and the formation of platelet-monocyte aggregates. Blood samples from one patient proofed positive concomitantly with the thromboembolic event. However, serological characteristics did not differ between antibodies associated with thromboembolic events from those without.
  
  
  CONCLUSIONS
  These data show that protamine-induced antibodies are specific and may induce platelet activation, which explains their association with thromboembolic events.
authors.forename: Simon
authors.initials: S
authors.lastname: Panzer
authors.forename: Arno
authors.initials: A
authors.lastname: Schiferer
authors.forename: Barbara
authors.initials: B
authors.lastname: Steinlechner
authors.forename: Ludovic
authors.initials: L
authors.lastname: Drouet
authors.forename: Jean
authors.initials: J
authors.lastname: Amiral
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies / Q000097:blood / Q000276:immunology*; D019411:Clinical Laboratory Techniques; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007362:Intensive Care Units; D007962:Leukocytes / Q000276:immunology; D008297:Male; D008875:Middle Aged; D015539:Platelet Activation / Q000276:immunology; D011479:Protamines / Q000009:adverse effects / Q000097:blood / Q000276:immunology*; D013921:Thrombocytopenia / Q000097:blood / Q000150:complications / Q000276:immunology*; D013927:Thrombosis / Q000097:blood / Q000150:complications / Q000276:immunology*
chemical_list: D000906:Antibodies; D011479:Protamines