Myocardial HLA-G reliably indicates a low risk of acute cellular rejection in heart transplant recipients.
BACKGROUND
Human leukocyte antigen-G (HLA-G), a non-classical MHC I protein with restricted tissue expression, plays an essential role in immune tolerance and has been negatively associated with acute and chronic rejection after heart transplantation. We assessed myocardial HLA-G expression in adult heart transplant patients in an attempt to determine the value of this protein in identifying patients with a low risk of acute cellular rejection.


METHODS
Two groups of patients were included in this study. Group A (non-rejecting) included 29 patients who had no moderate or severe rejection episodes (ISHLT Grade <2R) post-transplant. Group B (rejecting) included 38 patients with at least two moderate or severe rejection episodes (Grade >or=2R) within a 1-year period. Expression of HLA-G in three myocardial biopsies post-transplant from each patient was determined through immunohistochemical staining.


RESULTS
In Group A, 86% of patients had HLA-G(+) biopsies compared with 11% of patients in Group B (p < 0.001; sensitivity 86%, specificity 87%). Whereas 60% of non-rejecting HLA-G(+) patients had at least two positive biopsies, all rejecting HLA-G(+) patients had only one positive biopsy.


CONCLUSIONS
There is a significant negative association between myocardial HLA-G expression and acute cellular rejection after cardiac transplantation. Detection of HLA-G appears to reliably indicate a low risk of developing moderate or severe allograft rejection and may, subsequently, allow for a reduced immunosuppressive regimen.
Sheshgiri
Rohit
R
Heart Transplant Program, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada.
Rouas-Freiss
Nathalie
N
Rao
Vivek
V
Butany
Jagdish
J
Ramzy
Danny
D
Krawice-Radanne
Irene
I
Ross
Heather J
HJ
Carosella
Edgardo D
ED
Delgado
Diego H
DH
D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D015870:Gene Expression; D006084:Graft Rejection / Q000235:genetics* / Q000276:immunology*; D006680:HLA Antigens / Q000276:immunology*; D059951:HLA-G Antigens; D016027:Heart Transplantation / Q000276:immunology*; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D012307:Risk Factors
D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I