title: Platelet donor selection for HLA-immunised patients; the impact of donor-specific HLA antibody levels.
abstract: BACKGROUND
  Approximately 20% of patients with a recurrently poor platelet transfusion increment show human leukocyte antigen (HLA) alloantibodies. The aim of this study was to analyse the impact of mean fluorescence intensity (MFI) levels of donor-specific HLA antibodies and the feasibility of the HLAMatchmaker algorithm in donor selection.
  
  
  METHODS
  A total of 270 HLA-typed platelet transfusion responses of 40 patients were included in the study. The patients' immunisation status was determined with Luminex-based methods, and HLA alloantibody strengths were defined as the MFI. For the Matchmaker eplet matching, the HLA-ABC Eplet Matching Version 2.1 was used.
  
  
  RESULTS
  In 62% of the 270 transfusions, HLA antibodies against the transfused platelets were present, with a median cumulative MFI level of 2026 (range: 299-29 203). In multivariate analysis, a cumulative MFI level higher than 1000 emerged as an independent risk factor for a poor platelet transfusion increment, along with infection and the age of the product.
  
  
  CONCLUSIONS
  The HLAMatchmaker algorithm alone is not a sufficient tool for donor selection. Donor selection based primarily on the levels of donor-specific HLA antibodies is a preferable practice.
authors.affiliation: Clinical Consultations Finnish Red Cross Blood Service, Helsinki University Hospital, Helsinki, Finland.
authors.forename: T
authors.identifier: http://orcid.org/0000-0002-8694-0452
authors.initials: T
authors.lastname: Linjama
authors.affiliation: Comprehensive Cancer Center, Stem Cell Transplantation Unit, Helsinki University Hospital, Helsinki, Finland.
authors.forename: R
authors.initials: R
authors.lastname: Niittyvuopio
authors.affiliation: Clinical Consultations Finnish Red Cross Blood Service, Helsinki University Hospital, Helsinki, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Tuimala
authors.affiliation: Department of Medicine, Kuopio University Hospital, Kuopio, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Pyörälä
authors.affiliation: Department of Internal Medicine, Tampere University Hospital, Tampere, Finland.
authors.forename: H
authors.initials: H
authors.lastname: Rintala
authors.affiliation: Department of Internal Medicine, Tampere University Hospital, Tampere, Finland.|Institute of Clinical Medicine Oulu University Hospital, Oulu, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Rimpiläinen
authors.affiliation: Department of Internal Medicine, Turku University Hospital, Turku, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Kauppila
authors.affiliation: Clinical Consultations Finnish Red Cross Blood Service, Helsinki University Hospital, Helsinki, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Peräsaari
authors.affiliation: Clinical Consultations Finnish Red Cross Blood Service, Helsinki University Hospital, Helsinki, Finland.
authors.forename: E
authors.initials: E
authors.lastname: Juvonen
mesh_terms: D000465:Algorithms; D001782:Blood Donors; D046148:Donor Selection / Q000379:methods*; D005260:Female; D006680:HLA Antigens / Q000097:blood / Q000276:immunology; D006801:Humans; D007518:Isoantibodies / Q000097:blood / Q000276:immunology; D008297:Male; D017713:Platelet Transfusion
chemical_list: D006680:HLA Antigens; D007518:Isoantibodies
keywords: HLA alloimmunisation; HLA antibody level; HLAMatchmaker; platelet donor selection; platelet transfusion