title: Major histocompatibility complex class II antigen expression in rejecting cardiac allografts: detection using in vivo imaging with radiolabeled monoclonal antibody.
abstract: BACKGROUND
  Increased expression of major histocompatibility complex class II (MHC-II) antigen occurs during cardiac allograft rejection. We tested the hypotheses that (1) radiolabeled antibody to MHC-II antigen allows detection of cardiac allograft rejection using nuclear imaging techniques and (2) uptake of radiolabeled antibody to MHC-II antigen correlates with severity of rejection.
  
  
  RESULTS
  Thirteen beagles with cervical cardiac allografts were studied for 64+/-23 days by use of myocardial biopsy and in vivo imaging. Uptake of radiolabeled (131I [n=2], 123I [n=1], or 111In [n=10]) antibody to MHC-II increased over baseline in 7 animals that developed histological evidence of progressively worsening allograft rejection (group A), from 72.2+/-46.1 to 176.8+/-102.0 counts/pixel/mCi (P<.009). In 4 beagles without progressively worsening allograft rejection (group B), uptake was unchanged during follow-up (74.4+/-43.8 and 60.2+/-37.4 counts/pixel/mCi; P=NS). In animals studied with 111In-labeled antibody, uptake increased from 102.9+/-23.1 at baseline to 233.2+/-82.7 counts/pixel/mCi at follow-up in group A animals (P=.036), with no significant change in group B (91.1+/-34.9 and 75.9+/-24.9 counts/pixel/mCi; P=NS). Uptake of 111In-labeled antibody was 107.5+/-35.7, 135.9+/-70.8, and 307.8+/-90.1 counts/pixel/mCi in biopsy samples showing evidence of mild, moderate, and severe rejection, respectively (P=.001). Biopsy samples showing mild, moderate, and intense MHC-II expression antibody uptake had uptakes of 92.6+/-36.3, 158.5+/-54.7, and 307.8+/-90.1 counts/pixel/mCi, respectively (P=.00004).
  
  
  CONCLUSIONS
  Radiolabeled monoclonal antibodies to MHC-II antigen can detect cardiac allograft rejection in this large mammal model of cardiac allograft transplantation, and this technique may have a potential role in the detection of rejection in patients after cardiac transplantation.
authors.affiliation: University of Texas-Houston Medical School, 77225, USA. mcghie@heart.med.uth.tmc.edu
authors.forename: A I
authors.initials: AI
authors.lastname: McGhie
authors.forename: B
authors.initials: B
authors.lastname: Radovancevic
authors.forename: P
authors.initials: P
authors.lastname: Capek
authors.forename: W H
authors.initials: WH
authors.lastname: Moore
authors.forename: L
authors.initials: L
authors.lastname: Kasi
authors.forename: L
authors.initials: L
authors.lastname: Lamki
authors.forename: F J
authors.initials: FJ
authors.lastname: Clubb
authors.forename: O H
authors.initials: OH
authors.lastname: Frazier
authors.forename: J T
authors.initials: JT
authors.lastname: Willerson
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D004285:Dogs; D006084:Graft Rejection / Q000276:immunology* / Q000473:pathology / Q000503:physiopathology; D016027:Heart Transplantation / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000032:analysis / Q000276:immunology*; D007205:Indium Radioisotopes; D012720:Severity of Illness Index; D014184:Transplantation, Homologous
chemical_list: D000911:Antibodies, Monoclonal; D000949:Histocompatibility Antigens Class II; D007205:Indium Radioisotopes