title: Eosinophil count, allergies, and rejection in pediatric heart transplant recipients.
abstract: BACKGROUND
  Allograft rejection and long-term immunosuppression remain significant challenges in pediatric heart transplantation. Pediatric recipients are known to have fewer rejection episodes and to develop more allergic conditions than adults. A T-helper 2 cell dominant phenotype, manifested clinically by allergies and an elevated eosinophil count, may be associated with immunologic quiescence in transplant recipients. This study assessed whether the longitudinal eosinophil count and an allergic phenotype were associated with freedom from rejection.
  
  
  METHODS
  This single-center, longitudinal, observational study included 86 heart transplant patients monitored from 1994 to 2011. Post-transplant biannual complete blood counts, allergic conditions, and clinical characteristics related to rejection risk were examined.
  
  
  RESULTS
  At least 1 episode of acute cellular rejection (ACR) occurred in 38 patients (44%), antibody-mediated rejection (AMR) occurred in 11 (13%), and 49 patients (57%) were diagnosed with an allergic condition. Patients with ACR or AMR had a lower eosinophil count compared with non-rejectors (p = 0.011 and p = 0.022, respectively). In the multivariable regression analysis, the presence of panel reactive antibodies to human leukocyte antigen I (p = 0.014) and the median eosinophil count (p = 0.011) were the only independent covariates associated with AMR. Eosinophil count (p = 0.010) and female sex (p = 0.009) were independent risk factors for ACR. Allergic conditions or young age at transplant were not protective from rejection.
  
  
  CONCLUSIONS
  This study demonstrates a novel association between a high eosinophil count and freedom from rejection. Identifying a biomarker for low rejection risk may allow a reduction in immunosuppression. Further investigation into the role of the T-helper 2 cell phenotype and eosinophils in rejection quiescence is warranted.
authors.affiliation: School of Medicine.
authors.forename: Kate S
authors.initials: KS
authors.lastname: Arbon
authors.affiliation: Department of Pediatrics, Seattle Children's Hospital, University of Washington, Seattle, Washington.
authors.forename: Erin
authors.initials: E
authors.lastname: Albers
authors.affiliation: Department of Pediatrics, Seattle Children's Hospital, University of Washington, Seattle, Washington.
authors.forename: Mariska
authors.initials: M
authors.lastname: Kemna
authors.affiliation: Department of Pediatrics, Morgan Stanly Children's Hospital, Columbia University, New York, New York.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Law
authors.affiliation: Department of Pediatrics, Seattle Children's Hospital, University of Washington, Seattle, Washington. Electronic address: yuk.law@seattlechildrens.org.
authors.forename: Yuk
authors.initials: Y
authors.lastname: Law
mesh_terms: D002648:Child; D002675:Child, Preschool; D004804:Eosinophils; D005260:Female; D006084:Graft Rejection / Q000097:blood / Q000453:epidemiology*; D006333:Heart Failure / Q000097:blood* / Q000150:complications* / Q000601:surgery; D016027:Heart Transplantation; D006801:Humans; D006967:Hypersensitivity / Q000097:blood / Q000150:complications*; D007223:Infant; D007958:Leukocyte Count; D008137:Longitudinal Studies; D008297:Male; D012189:Retrospective Studies
keywords: T helper phenotypes and rejection; allergies; pediatric heart transplantation; rejection