Major histocompatibility complex class II antigen expression in rejecting cardiac allografts: detection using in vivo imaging with radiolabeled monoclonal antibody.
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.
McGhie
A I
AI
University of Texas-Houston Medical School, 77225, USA. mcghie@heart.med.uth.tmc.edu
Radovancevic
B
B
Capek
P
P
Moore
W H
WH
Kasi
L
L
Lamki
L
L
Clubb
F J
FJ
Frazier
O H
OH
Willerson
J T
JT
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
D000911:Antibodies, Monoclonal; D000949:Histocompatibility Antigens Class II; D007205:Indium Radioisotopes