title: Warm-reactive (immunoglobulin G) autoantibodies and laboratory testing best practices: review of the literature and survey of current practice.
abstract: Warm-reactive autoantibodies (WAAs) are the most common cause of autoimmune hemolytic anemia (AIHA) and can also be present without clinically significant hemolysis. WAAs complicate immunohematological testing, yet there is no commonly accepted approach to laboratory evaluation and red blood cell (RBC) selection.
  
  
  
  We searched PubMed/Cochrane Central for articles that described testing methodology and blood selection for patients with WAAs. We developed a 31-question survey regarding local practice for immunohematology testing and RBC selection in patients with WAAs (with or without AIHA).
  
  
  
  Eighty-six studies met the inclusion criteria and the aims of this review. Most of the literature was comprised of retrospective studies that often did not correlate laboratory results with clinical findings. Evidence-based protocols to guide testing and RBC selection for transfusion in patients with WAAs are lacking. Individuals representing 54 laboratories completed the survey. The responses indicated that numerous methodologies are used to identify underlying alloantibodies: 75% of respondents use autoadsorption; in patients who have a recent history of transfusion, 76% of respondents use alloadsorption; 58% of respondents perform direct antiglobulin testing (DAT) each time the indirect antiglobulin test is positive; and 48% perform eluate studies at the initial identification of WAAs. Responding laboratories may use phenotyping (98%) or genotyping (80%) at some point in the work-up. Seventy-five percent of respondents provide phenotype-matched or genotype-matched RBCs for transfusion.
  
  
  
  There is wide variability in immunohematology testing and RBC selection practices for patients who have WAAs (with or without AIHA). Future studies are needed to evaluate and compare the effectiveness of different testing algorithms and transfusion strategies.
authors.affiliation: Wing-Kwai and Alice Lee-Tsing Chung Transfusion Service, Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California.
authors.forename: Alyssa
authors.initials: A
authors.lastname: Ziman
authors.affiliation: Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota.
authors.forename: Claudia
authors.initials: C
authors.lastname: Cohn
authors.affiliation: Hoxworth Blood Center and Department of Pathology and Laboratory Medicine, University of Cincinnati, Ohio.
authors.forename: Patricia M
authors.initials: PM
authors.lastname: Carey
authors.affiliation: Departments of Pathology and Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire.
authors.forename: Nancy M
authors.initials: NM
authors.lastname: Dunbar
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Vermont Medical Center, Burlington, Vermont.
authors.forename: Mark K
authors.initials: MK
authors.lastname: Fung
authors.affiliation: Department of Immunology and Transfusion Medicine, Ernst-Moritz-Arndt-University, Greifswald, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Greinacher
authors.affiliation: National Health Service (NHS) Blood and Transplant/Oxford University Hospitals NHS Trust, John Radcliffe Hospital, Oxford, United Kingdom; the Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.
authors.forename: Simon
authors.initials: S
authors.lastname: Stanworth
authors.affiliation: Faculty of Health Sciences, Department of Medicine, , Canadian Blood Services, McMaster University, and Centre for Innovation, Hamilton, Ontario, Canada.
authors.forename: Nancy M
authors.initials: NM
authors.lastname: Heddle
authors.affiliation: Bloodworks NW, Seattle Washington.|Department of Laboratory Medicine, University of Washington, Seattle, Washington.
authors.forename: Meghan
authors.initials: M
authors.lastname: Delaney
mesh_terms: D000744:Anemia, Hemolytic, Autoimmune / Q000097:blood*; D001323:Autoantibodies / Q000097:blood*; D046148:Donor Selection / Q000379:methods*; D017707:Erythrocyte Transfusion; D004912:Erythrocytes; D005260:Female; D006461:Hemolysis; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D039781:PubMed
chemical_list: D001323:Autoantibodies; D007074:Immunoglobulin G