title: Clinically irrelevant circulating human leukocyte antigen antibodies in the presence of ventricular assist devices.
abstract: BACKGROUND
  Identification of anti-human leukocyte antigen (HLA) antibodies by single-antigen beads (SAB) allows for prediction of donor-specific crossmatches (virtual crossmatches), thus facilitating the allocation of organs from deceased donors. However, the clinical relevance of HLA antibodies identified by SAB has been less than clear. This study demonstrates that sera from cardiac transplant candidates with a ventricular assist device (VAD) or infection may contain clinically irrelevant antibodies that bind to the beads but not to lymphocytes.
  
  
  METHODS
  Investigated were 5 cardiac transplant candidates (3 with VAD, all with infections, and 1 retransplant) with positive HLA antibodies detected by SAB, but negative by cytotoxicity. To determine clinical relevance of the antibodies, flow cytometric crossmatches (FCXM) were performed. Untreated beads and elution buffer-treated beads to dissociate the β-2 microglobulin and the peptide from the heavy chain were used.
  
  
  RESULTS
  The virtual crossmatch data were compared with data from actual FCXMs. Of 40 T-cell and B-cell FCXM, SAB-identified HLA antibodies were predictive for only 1 T-cell and 9 B-cell FCXM outcomes. Patients' sera contained a mixture of antibodies directed against cryptic epitopes on the heavy chain and exposed epitopes. The mean fluorescence intensity of antibodies varied from 1,040 to 11,000.
  
  
  CONCLUSIONS
  Sera from cardiac transplant candidates with or without VAD may contain natural antibodies that do not bind to intact antigens on the cell surface. Therefore, great care must be exercised before denying a life-saving transplant to these patients simply on the basis of SAB results.
authors.affiliation: Texas Medical Specialty, Inc, 7777 Forest Lane, Dallas, TX 75230, USA. nikaein@cs.com
authors.forename: Afzal
authors.initials: A
authors.lastname: Nikaein
authors.forename: Nadim
authors.initials: N
authors.lastname: El-Awar
authors.forename: Judson
authors.initials: J
authors.lastname: Hunt
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Rosenthal
authors.forename: Eric
authors.initials: E
authors.lastname: Eichhorn
authors.forename: Shelly
authors.initials: S
authors.lastname: Hall
authors.forename: James
authors.initials: J
authors.lastname: Boehrer
authors.forename: Mitchell
authors.initials: M
authors.lastname: Magee
authors.forename: Marc
authors.initials: M
authors.lastname: Pieniek
authors.forename: William
authors.initials: W
authors.lastname: Brinkman
authors.forename: Todd
authors.initials: T
authors.lastname: Dewey
mesh_terms: D000906:Antibodies / Q000097:blood*; D001402:B-Lymphocytes / Q000276:immunology; D001788:Blood Grouping and Crossmatching / Q000379:methods*; D005434:Flow Cytometry; D006680:HLA Antigens / Q000276:immunology*; D016027:Heart Transplantation / Q000276:immunology*; D006353:Heart-Assist Devices; D006801:Humans; D007239:Infections / Q000276:immunology; D012189:Retrospective Studies; D013601:T-Lymphocytes / Q000276:immunology; D014946:Wound Infection / Q000276:immunology
chemical_list: D000906:Antibodies; D006680:HLA Antigens