Correlation of Fas and Fas ligand expression with rejection status of transplanted heart in human

Background, Activation of pro-apoptotic systems has been proven in rejectio n model of animal heart transplantation. The role of Fas and Fas ligand (Fa sL) in graft rejection is not fully understood, and the expression changes of these genes in human transplanted heart have not been elucidated. Methods. Endomyocardial biopsy samples were taken from 13 consecutive patie nts undergoing heart transplantation at various times, and they were classi fied into rejection (REJ, grade 3A or more) and lack of rejection (TOL, gra de 1B or less) by International Society of Heart and Lung Transplantation r ejection grade. Semiquantitative reverse transcription-polymerase chain rea ction and immunohistochemistry were performed to evaluate the status of Fas and FasL expression in each sample, Results. Fas was constitutively expressed both in REJ and TOL specimens (ex pression levels normalized by glyceraldehyde-3-phosphate dehydrogenase expr ession in semiquantitative reverse transcription-polymerase chain reaction of REJ vs. TOL, 0.842+/-0.096 vs. 0.848+/-0.103, P=0.776); however, FasL ex pression was detected in 66% of REJ samples and 40% of TOL samples. Normali zed levels of FasL expression were 0.591+/-0.494 (REJ) and 0.383+/-0.507 (T OL) (P<0.05). FasL was expressed by cardiomyocytes as well as graft-infiltr ating cells. Conclusions. This up-regulation of FasL may be one of possible mechanisms o f apoptosis in rejection process of human cardiac allograft.