title: Panel-reactive antibodies late after allograft implantation in children.
abstract: BACKGROUND
  Circulating human leukocyte antigen (HLA) panel-reactive antibodies (PRA > 10%) have been independently associated with increased risk of rejection and mortality in patients who undergo cardiac transplantation. Cryopreserved allografts used to repair heart defects induce broadly reactive HLA antibodies in children that persist for an undetermined duration of time. The purpose of this study was to prospectively determine the level of HLA sensitization several years after implantation of cryopreserved allografts in children.
  
  
  METHODS
  We conducted late follow-up of 13 children previously screened for PRA before and after implantation of valved and nonvalved allografts who are alive and free from allograft replacement. Panel-reactive antibodies against HLA class I and II antigens were determined using flow cytometry and classified as high reactive (>50% PRA), low reactive (11% to 50%), or absent (0% to 10%). Follow-up PRA was compared with PRA obtained 3 months after initial allograft implantation.
  
  
  RESULTS
  Elevated HLA class I PRA persisted at late follow-up in 12 of 13 children, although it decreased significantly from high to low or from low to absent in 12 of 13 patients (p < 0.001). Elevated HLA class II PRA persisted at late follow-up in 6 of 13 children (46%) and had decreased significantly from prior levels (p = 0.011).
  
  
  CONCLUSIONS
  Circulating HLA antibodies induced by cryopreserved allograft tissue persist up to 8 years after implantation although they decrease with time. Therefore, children who have received cryopreserved allografts before cardiac transplantation may be at greater risk for transplant rejection.
authors.affiliation: Department of Pediatrics, University of Utah School of Medicine and Primary Children's Medical Center, Salt Lake City, Utah 84113, USA.
authors.forename: David K
authors.initials: DK
authors.lastname: Hooper
authors.forename: John A
authors.initials: JA
authors.lastname: Hawkins
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Fuller
authors.forename: Tracie
authors.initials: T
authors.lastname: Profaizer
authors.forename: Robert E
authors.initials: RE
authors.lastname: Shaddy
mesh_terms: D002648:Child; D002675:Child, Preschool; D015925:Cryopreservation; D005260:Female; D005500:Follow-Up Studies; D006680:HLA Antigens / Q000276:immunology*; D006330:Heart Defects, Congenital / Q000601:surgery; D006351:Heart Valves / Q000637:transplantation*; D006801:Humans; D007223:Infant; D008297:Male; D011446:Prospective Studies; D014184:Transplantation, Homologous / Q000276:immunology*
chemical_list: D006680:HLA Antigens