title: Blood Group A antigen expression on cardiac endothelium is highly individualized: possible implications for transplantation.
abstract: BACKGROUND
  Outcomes in cases of adult accidental ABO incompatible cardiac transplantation are highly variable, with some patients suffering nearly immediate catastrophic antibody-mediated rejection while others (~37%-45%) survive. We hypothesize that these disparate outcomes could be influenced by variations in blood group antigen expression on allograft endothelium.
  
  
  METHODS
  Immunohistochemical stains for blood Group A antigen were performed on cardiac tissue from 18 blood Type A cadavers. Staining was evaluated by two distinct modalities: semiquantitative light microscopy, which measured the intensity of antigen expression on endothelium, and quantitative digital analysis, which determined the percentage of the total tissue section area staining positive for blood Group A antigen. These data were used to compute a Comprehensive Expression Index (CEI) of blood Group A antigen expression for each specimen.
  
  
  RESULTS
  Semiquantitative light microscopic examination determined that endothelium was stained with low intensity in four (22%) myocardial samples, intermediate intensity in five (28%) samples, and high intensity in nine (50%) samples. Quantitative digital analysis revealed a range in the percentage of total cross sectional area composed of blood Group A-positive signal (median, 2.69%; interquartile range, 1.68%-2.94%). Increased percentage of total cross sectional area composed of blood Group A-positive signal was positively associated with patient age (P=.0037). The CEI showed a broad range, with a median of 5.27 and an interquartile range of 2.92-8.22.
  
  
  CONCLUSIONS
  There are little data available regarding interindividual differences in blood Group A antigen expression in cardiac endothelium. Here, we report interindividual variation in endothelial expression of blood Group A antigen in 18 specimens. These variations may help to explain disparate outcomes in cases of accidental ABO incompatible cardiac transplantation in adults.
authors.affiliation: Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Gehrie
authors.forename: Justin M
authors.initials: JM
authors.lastname: Cates
authors.forename: Hui
authors.initials: H
authors.lastname: Nian
authors.forename: Sandy J
authors.initials: SJ
authors.lastname: Olson
authors.forename: Pampee P
authors.initials: PP
authors.lastname: Young
mesh_terms: D000017:ABO Blood-Group System; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001787:Blood Group Incompatibility / Q000276:immunology; D002102:Cadaver; D002648:Child; D003331:Coronary Vessels / Q000276:immunology*; D004730:Endothelium, Vascular / Q000276:immunology*; D005260:Female; D006084:Graft Rejection / Q000276:immunology; D016027:Heart Transplantation / Q000009:adverse effects; D006648:Histocompatibility; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D000017:ABO Blood-Group System
keywords: ABO incompatibility; Antibody-mediated rejection; Blood type incompatible transplant; Cardiac transplant; Immunohistochemistry