title: Defining unacceptable HLA antigens.
abstract: OBJECTIVE
  Neither the concept nor the formal application of unacceptable antigens is new. However, identification of unacceptable antigens is now sufficiently accurate to be used as a virtual crossmatch, which can both prevent the unnecessary shipment of organs and increase the access for sensitized patients.
  
  
  RESULTS
  Desensitization protocols and an increasing array of cell-depleting agents can overcome the immunological barriers to transplantation for some patients, reducing the risk of graft rejection to an acceptable level. Increasingly sensitive and specific assays for identifying HLA antigens and antibodies are providing more accurate definition of incompatibilities. Additionally, tests of various biomarkers may permit characterization of responder types.
  
  
  CONCLUSIONS
  The definition of unacceptable antigens is determined by the clinical protocols and the physiological and immunological characteristics of the recipient and donor. These data should be integrated to maximize the opportunity for transplantation. The development of additional tests to assess a patient's capacity for recognizing and responding to a transplant will improve the identification of incompatible donor-recipient pairs.
authors.affiliation: Department of Medicine, The Johns Hopkins School of Medicine, Baltimore, Maryland, USA.
authors.forename: Andrea A
authors.initials: AA
authors.lastname: Zachary
authors.forename: Robert A
authors.initials: RA
authors.lastname: Montgomery
authors.forename: Mary S
authors.initials: MS
authors.lastname: Leffell
mesh_terms: D000906:Antibodies / Q000097:blood*; D000918:Antibody Specificity; D000075202:Contraindications; D003888:Desensitization, Immunologic; D006084:Graft Rejection / Q000276:immunology / Q000517:prevention & control*; D006680:HLA Antigens / Q000097:blood*; D006648:Histocompatibility; D006650:Histocompatibility Testing; D006801:Humans; D016377:Organ Transplantation; D011237:Predictive Value of Tests; D018570:Risk Assessment; D012307:Risk Factors; D023001:Transplantation Tolerance
chemical_list: D000906:Antibodies; D006680:HLA Antigens