title: Pathologic classification of antibody-mediated rejection correlates with donor-specific antibodies and endothelial cell activation.
abstract: BACKGROUND
  Humoral immune responses during heart transplantation may result in antibody-mediated rejection (AMR), which is now taken into account on endomyocardial biopsy (EMB) specimens and ranked according to the pathologic AMR (pAMR) grades of the International Society for Heart and Lung Transplantation classification. This classification might benefit from new immunohistological markers and validation by others biomarkers, namely donor-specific antibodies (DSA).
  
  
  METHODS
  From the 293 protocol EMBs performed in 113 patients in our institution during a 1-year period for this prospective study, 280 EMB specimens were available with both histology and immunohistochemistry. C4d and labeling of intravascular cells by cluster of differentiation (CD) 68 were performed on paraffin sections. Available sera (n = 150) concomitant of EMB specimens were tested for the presence of DSA. All of the pAMR+ EMB specimens, along with a set of randomized pAMR0 EMB specimens, were immunolabeled for mammalian target of rapamycin (mTOR) effectors, phosphorylated 70 S6-kinase (p70S6K) and phosphorylated S6 ribosomal protein (pS6RP).
  
  
  RESULTS
  AMR was diagnosed in 37 EMB specimens (13.2%): 1 pAMR1(I+), 27 pAMR1(H+), and 9 pAMR2. The proportion of DSA-positive EMB varied according to the pAMR grade, with pAMR0, pAMR1(H+), and pAMR2 EMB presenting 17.6%, 77.3%, and 100% of DSA-positivity, respectively. Among the 30 pAMR+ specimens with available DSA testing and the 30 pAMR0 randomized specimens, mTOR pathway immunohistochemistry showed endothelial cell positivity for p70S6K in 17 pAMR+ EMB specimens (56.7%) and in 1 pAMR0 EMB specimen (3.3%). pS6RP was detected in 8 pAMR+ EMB specimens (26.7%) and in 1 pAMR0 EMB specimen (3.3%).
  
  
  CONCLUSIONS
  p70S6K and pS6RP immunohistochemistry afford new markers of AMR on EMB specimens because their expression is correlated with microcirculation inflammation and DSA. The correlation of DSA with pAMR grade suggests that this grading system is valid.
authors.affiliation: Université Paris Descartes Médecine, Paris, France.
authors.forename: Marion
authors.initials: M
authors.lastname: Tible
authors.forename: Alexandre
authors.initials: A
authors.lastname: Loupy
authors.forename: Dewi
authors.initials: D
authors.lastname: Vernerey
authors.forename: Caroline
authors.initials: C
authors.lastname: Suberbielle
authors.forename: Thibaut
authors.initials: T
authors.lastname: Beuscart
authors.forename: Aurelie
authors.initials: A
authors.lastname: Cazes
authors.forename: Romain
authors.initials: R
authors.lastname: Guillemain
authors.forename: Catherine
authors.initials: C
authors.lastname: Amrein
authors.forename: Veronique
authors.initials: V
authors.lastname: Pezzella
authors.forename: Jean-Noel
authors.initials: JN
authors.lastname: Fabiani
authors.forename: Dominique
authors.initials: D
authors.lastname: Nochy
authors.forename: Gary
authors.initials: G
authors.lastname: Hill
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Empana
authors.forename: Xavier
authors.initials: X
authors.lastname: Jouven
authors.forename: Dominique
authors.initials: D
authors.lastname: Charron
authors.forename: Patrick
authors.initials: P
authors.lastname: Bruneval
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Duong Van Huyen
mesh_terms: D000328:Adult; D000906:Antibodies / Q000276:immunology*; D042783:Endothelial Cells / Q000276:immunology*; D005260:Female; D006084:Graft Rejection / Q000145:classification / Q000276:immunology* / Q000473:pathology*; D016027:Heart Transplantation / Q000276:immunology* / Q000473:pathology*; D006801:Humans; D008297:Male; D011446:Prospective Studies; D014019:Tissue Donors
chemical_list: D000906:Antibodies
keywords: antibody-mediated rejection; donor-specific antibodies; endomyocardial biopsy; heart transplantation; microcirculation inflammation; pAMR