title: ABO-incompatible hearts for infant transplantation.
abstract: OBJECTIVE
  The practice of offering ABO-incompatible (ABOi) heart transplantation during infancy was initiated based on the rationale that infants are at the highest risk of dying while waiting for a transplant, yet are at low risk of hyperacute antibody-mediated rejection due to immunologic immaturity. Since the first report of intentional ABOi heart transplantation a decade ago, its success has been corroborated in numerous reports and the practice has been widely adopted. This review summarizes clinical results in reports of ABOi transplantation and the evolution of ABOi listing strategies, as well as evidence of immune tolerance after ABOi transplantation.
  
  
  RESULTS
  Recent reports have documented comparable midterm and long-term clinical outcomes in ABOi and ABO-compatible (ABOc) heart transplant recipients in terms of survival and posttransplant complications. Despite successful outcomes, however, there are obstacles to widespread implementation of ABOi transplantation in the USA and in some European centers. The notable deficiency in development of antibody production to donor A/B antigens following ABOi transplantation described in early reports has been corroborated, with some exceptions. Potential advantages of ABOi transplantation are emerging as well as innovative strategies that may allow ABOi heart transplantation beyond the age of infancy.
  
  
  CONCLUSIONS
  ABOi heart transplantation is one example in which immunologic immaturity has been exploited to the advantage of pediatric transplant recipients. In-depth exploration of transplant-related immunobiology in the young may reveal further opportunities.
authors.affiliation: Department of Pediatrics, University of Alberta, Stollery Childrens Hospital, Edmonton, Alberta, Canada. ljwest@ualberta.ca
authors.forename: Lori J
authors.initials: LJ
authors.lastname: West
mesh_terms: D000017:ABO Blood-Group System / Q000276:immunology*; D046148:Donor Selection / Q000379:methods*; D005060:Europe / Q000453:epidemiology; D006084:Graft Rejection / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control; D006085:Graft Survival / Q000276:immunology*; D016027:Heart Transplantation / Q000276:immunology*; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology*; D015994:Incidence; D007223:Infant; D014481:United States / Q000453:epidemiology
chemical_list: D000017:ABO Blood-Group System