title: Platelet activation in the presence of neutral protamine Hagedorn insulin: a new feature of antibodies against protamine/heparin complexes.
abstract: Essentials Protamine (PRT) is used to stabilize insulin in neutral protamine Hagedorn (NPH) insulin. The interaction between NPH-insulin, anti-PRT/heparin antibodies and platelets was investigated. Anti-PRT/heparin antibodies activate platelets in presence of NPH-insulin dependent on heparin. Cross-reactivity seems to have no major effect on the clinical outcome of medical patients.
  
  
  
  Background Protamine (PRT) is used to stabilize insulin in neutral protamine Hagedorn (NPH) insulin, a commonly used therapeutic agent for diabetes mellitus. Immunization against PRT/heparin complexes is common in diabetic patients. Objectives To investigate the impact of NPH-insulin on the interaction between anti-PRT/heparin antibodies and platelets. Methods The interaction between NPH-insulin and anti-PRT/heparin antibodies was tested using in-house enzyme immunoassays. The ability of anti-PRT/heparin antibodies to activate platelets in the presence of NPH-insulin (and heparin) was investigated using flow cytometry. Results Twenty-one out of 80 sera containing anti-PRT/heparin IgG showed binding to NPH-insulin. Anti-PRT/heparin IgG from immunized patients bound to platelets in the presence of NPH-insulin, but not in the presence of native insulin. Anti-PRT/heparin antibodies induced P-selectin expression in the presence of NPH-insulin in a heparin-dependent way (median mean fluorescence intensity in the presence of NPH-insulin: 55, 95% confidence interval [CI] 18.7-100.5 vs. NPH-insulin and heparin: 204, 95% CI 106.5-372.8). The clinical relevance of platelet-activating anti-PRT/heparin antibodies was assessed by investigating a multicenter study cohort of 332 acutely ill medical patients who received heparin. None of the 21 patients with anti-PRT/heparin IgG developed thrombocytopenia or thromboembolic complications. Conclusions Anti-PRT/heparin antibodies activate platelets in the presence of NPH-insulin in a heparin-dependent way. However, results from our preliminary study indicate no major impact of these antibodies on the clinical outcome in medical patients receiving heparin, particularly on thromboembolic complications.
authors.affiliation: Institute for Immunology and Transfusion Medicine, Universitätsmedizin Greifswald, Greifswald.
authors.forename: H
authors.initials: H
authors.lastname: Zöllner
authors.affiliation: Institute for Immunology and Transfusion Medicine, Universitätsmedizin Greifswald, Greifswald.|Center for Clinical Transfusion Medicine, Universitätsklinikum Tübingen, Tübingen, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Jouni
authors.affiliation: Department for Blood Group Serology and Transfusion Medicine, Medical University Vienna, Vienna, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Panzer
authors.affiliation: Institute for Immunology and Transfusion Medicine, Universitätsmedizin Greifswald, Greifswald.
authors.forename: A
authors.initials: A
authors.lastname: Khadour
authors.affiliation: Institute for Immunology and Transfusion Medicine, Universitätsmedizin Greifswald, Greifswald.
authors.forename: L
authors.initials: L
authors.lastname: Janzen
authors.affiliation: Institute for Immunology and Transfusion Medicine, Universitätsmedizin Greifswald, Greifswald.
authors.forename: J
authors.initials: J
authors.lastname: Wesche
authors.affiliation: Department of Clinical Chemistry and Hematology, University of Utrecht, Utrecht, the Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Ten Berg
authors.affiliation: Medical Clinic II, Municipal Hospital of Dresden, Dresden, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Schellong
authors.affiliation: Aspen Germany GmbH, Munich, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Heinken
authors.affiliation: Institute for Immunology and Transfusion Medicine, Universitätsmedizin Greifswald, Greifswald.
authors.forename: A
authors.initials: A
authors.lastname: Greinacher
authors.affiliation: Institute for Immunology and Transfusion Medicine, Universitätsmedizin Greifswald, Greifswald.|Center for Clinical Transfusion Medicine, Universitätsklinikum Tübingen, Tübingen, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Bakchoul
mesh_terms: D000368:Aged; D000906:Antibodies / Q000737:chemistry*; D000925:Anticoagulants / Q000737:chemistry; D001792:Blood Platelets / Q000378:metabolism; D003920:Diabetes Mellitus / Q000188:drug therapy; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006493:Heparin / Q000737:chemistry*; D006801:Humans; D007118:Immunoassay; D007297:Inpatients; D007328:Insulin / Q000737:chemistry; D007336:Insulin, Isophane / Q000737:chemistry*; D008297:Male; D019007:P-Selectin / Q000378:metabolism; D015539:Platelet Activation; D011479:Protamines / Q000737:chemistry*
chemical_list: D000906:Antibodies; D000925:Anticoagulants; D007328:Insulin; D019007:P-Selectin; D011479:Protamines; C546937:SELP protein, human; D007336:Insulin, Isophane; D006493:Heparin
keywords: antigen-antibody complex; blood platelets; insulin; protamines; thrombocytopenia