title: Concordance and discordance in anti-HLA antibody testing.
abstract: BACKGROUND
  Correct identification of the specificity of antibodies directed against HLA using single antigen Luminex beads (SALB) is essential in current HLA laboratory practice for transplantation. The aim of this study was to investigate the magnitude of concordance and discordance among laboratories in testing for anti-HLA antibodies using SALB.
  
  
  METHODS
  35 sera were distributed by the ASHI Proficiency Testing Program to HLA laboratories worldwide. We analyzed 4335 test results submitted between April 2010 and April 2013 by participating laboratories.
  
  
  RESULTS
  SALB was used by approximately 94% of the participating laboratories, yet concordant assignment of antibody specificity was imperfect. For each serum, the assignment of an average of 10 antibody specificities was discordant. Disagreement was observed for antibodies directed against common as well as uncommon antigens. The assignment of an average of 15 antibody specificities in each "positive" serum appeared to be influenced by vendor-dependent causes. Inter-vendor concordance was lower than intra-vendor concordance, indicating that vendor dependent factors may be a central cause for disagreement.
  
  
  CONCLUSIONS
  Our study illustrates the prevalence of concordance and discordance, also affected by unpremeditated causes, in reporting SALB antibody results. Insufficient concordance and standardization in antibody testing may have practical implications for organ allocation and organ sharing programs.
authors.affiliation: Tissue Typing Laboratory, Rabin Medical Center, Beilinson Campus, Zabotinski Road, Petach-Tikva 49100, Israel; Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands. Electronic address: israelimoshe@yahoo.com.
authors.forename: Moshe
authors.initials: M
authors.lastname: Israeli
authors.affiliation: Department of Pathology, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
authors.forename: Marilyn S
authors.initials: MS
authors.lastname: Pollack
authors.affiliation: School of Medicine, Oregon Health & Science University, 2611 SW 3rd Ave Suite 360, Portland, OR 97239, USA.
authors.forename: Carley A E
authors.initials: CA
authors.lastname: Shaut
authors.affiliation: Histocompatibility Laboratory, University of Alberta Hospital, 8220-112 St, Edmonton, AB T6G 2B7, Canada.
authors.forename: Anne
authors.initials: A
authors.lastname: Halpin
authors.affiliation: Clinical Histocompatibility Lab, Wexner Medical Center, The Ohio State University, N943 Doan Hall, 410 W 10th Avenue, Columbus, OH 43210, USA.
authors.forename: Nicholas R
authors.initials: NR
authors.lastname: DiPaola
authors.affiliation: Puget Sound Blood Center, 921 Terry Ave., Seattle, WA 98104, USA.
authors.forename: Danny
authors.initials: D
authors.lastname: Youngs
authors.affiliation: Histocompatibility Laboratory, Massachusetts General Hospital, 55 Fruit St, Room GRJ 220, Boston, MA 02114, USA.
authors.forename: Susan L
authors.initials: SL
authors.lastname: Saidman
mesh_terms: D000906:Antibodies / Q000737:chemistry*; D005260:Female; D006680:HLA Antigens / Q000737:chemistry*; D006650:Histocompatibility Testing / Q000379:methods / Q000592:standards*; D006801:Humans; D008297:Male
chemical_list: D000906:Antibodies; D006680:HLA Antigens
keywords: ASHI; Antibodies; Consensus; HLA; Luminex; Proficiency testing