title: Characterization of a human platelet antigen-1a-specific monoclonal antibody derived from a B cell from a woman alloimmunized in pregnancy.
abstract: Human platelet Ag (HPA)-1a, located on integrin β3, is the main target for alloantibodies responsible for fetal and neonatal alloimmune thrombocytopenia (FNAIT) in the white population. There are ongoing efforts to develop an Ab prophylaxis and therapy to prevent or treat FNAIT. In this study, an mAb specific for HPA-1a, named 26.4, was derived from an immortalized B cell from an alloimmunized woman who had an infant affected by FNAIT. It is the only HPA-1a-specific human mAb with naturally paired H and L chains. Specific binding of mAb 26.4, both native and recombinant forms, to platelets and to purified integrins αIIbβ3 (from platelets) and αVβ3 (from trophoblasts) from HPA-1a(+) donors was demonstrated by flow cytometry and surface plasmon resonance technology, respectively. No binding to HPA-1a(-) platelets or integrins was detected. Moreover, the Ab binds with higher affinity to integrin αVβ3 compared with a second HPA-1a-specific human mAb, B2G1. Further in vitro experimentation demonstrated that mAb 26.4 can opsonize HPA-1a(+) platelets for enhanced phagocytosis by monocytes, inhibit binding of maternal polyclonal anti-HPA-1a Abs, and weakly inhibit aggregation of HPA-1a-heterozygous platelets, the latter with no predicted clinical relevance. Thus, mAb 26.4 is highly specific for HPA-1a and could potentially be explored for use as a prophylactic or therapeutic reagent for FNAIT intervention and as a phenotyping reagent to identify women at risk for immunization.
authors.affiliation: Immunology Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø - The Arctic University of Norway, N-9037 Tromsø, Norway;
authors.forename: Mariana
authors.initials: M
authors.lastname: Eksteen
authors.affiliation: Immunology Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø - The Arctic University of Norway, N-9037 Tromsø, Norway; Department of Obstetrics and Gynecology, University Hospital of North Norway, N-9038 Tromsø, Norway;
authors.forename: Heidi
authors.initials: H
authors.lastname: Tiller
authors.affiliation: Department of Laboratory Medicine, Diagnostic Clinic, University Hospital of North Norway, N-9038 Tromsø, Norway;
authors.forename: Maria
authors.initials: M
authors.lastname: Averina
authors.affiliation: Immunology Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø - The Arctic University of Norway, N-9037 Tromsø, Norway;
authors.forename: Gøril
authors.initials: G
authors.lastname: Heide
authors.affiliation: Immunology Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø - The Arctic University of Norway, N-9037 Tromsø, Norway; Department of Laboratory Medicine, Diagnostic Clinic, University Hospital of North Norway, N-9038 Tromsø, Norway; Prophylix Pharma AS, Forskningsparken, N-9294 Tromsø, Norway;
authors.forename: Mette
authors.initials: M
authors.lastname: Kjaer
authors.affiliation: Department of Haematology, University of Cambridge, Cambridge CB2 0XY, United Kingdom; National Health Service Blood and Transplant, Cambridge Biomedical Campus, Cambridge CB2 0PT, United Kingdom;
authors.forename: Cedric
authors.initials: C
authors.lastname: Ghevaert
authors.affiliation: The Norwegian Institute of Public Health, N-0403 Oslo, Norway; and School of Pharmacy, University of Oslo, N-0316 Oslo, Norway.
authors.forename: Terje E
authors.initials: TE
authors.lastname: Michaelsen
authors.affiliation: The Norwegian Institute of Public Health, N-0403 Oslo, Norway; and.
authors.forename: Øistein
authors.initials: Ø
authors.lastname: Ihle
authors.affiliation: Immunology Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø - The Arctic University of Norway, N-9037 Tromsø, Norway; Department of Laboratory Medicine, Diagnostic Clinic, University Hospital of North Norway, N-9038 Tromsø, Norway;
authors.forename: Anne
authors.initials: A
authors.lastname: Husebekk
authors.affiliation: Immunology Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø - The Arctic University of Norway, N-9037 Tromsø, Norway; Department of Laboratory Medicine, Diagnostic Clinic, University Hospital of North Norway, N-9038 Tromsø, Norway; Prophylix Pharma AS, Forskningsparken, N-9294 Tromsø, Norway;
authors.forename: Bjørn
authors.initials: B
authors.lastname: Skogen
authors.affiliation: Immunology Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø - The Arctic University of Norway, N-9037 Tromsø, Norway; tor.brynjar.stuge@uit.no.
authors.forename: Tor B
authors.initials: TB
authors.lastname: Stuge
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D000915:Antibody Affinity / Q000276:immunology; D000917:Antibody Formation / Q000276:immunology*; D000918:Antibody Specificity; D016824:Antigens, Human Platelet / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D001483:Base Sequence; D001792:Blood Platelets / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D002461:Cell Line, Transformed; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000235:genetics / Q000276:immunology; D007135:Immunoglobulin Variable Region / Q000737:chemistry / Q000235:genetics; D007156:Immunologic Memory; D039302:Integrin alphaVbeta3 / Q000378:metabolism; D039661:Integrin beta3; D007518:Isoantibodies / Q000276:immunology*; D008969:Molecular Sequence Data; D009154:Mutation; D010587:Phagocytosis / Q000187:drug effects / Q000276:immunology; D010974:Platelet Aggregation / Q000187:drug effects / Q000276:immunology; D011247:Pregnancy; D011485:Protein Binding / Q000276:immunology; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D016824:Antigens, Human Platelet; C061248:ITGB3 protein, human; D007074:Immunoglobulin G; D007135:Immunoglobulin Variable Region; D039302:Integrin alphaVbeta3; D039661:Integrin beta3; D007518:Isoantibodies; D011994:Recombinant Proteins