Complement activation products in plasma after heart transplantation in humans

Background Complement activation has recently been implicated as a contribu ting factor to early and late allograft dysfunction in cardiac transplantat ion. The current study was designed to determine whether measurement of pla sma complement fragments C4d and SC5b-9 would be useful in detecting acute rejection or accelerated graft atherosclerosis (AGA) in cardiac allograft r ecipients. Methods. We measured complement activation products, C4d (classical pathway ) and SC5b-9 (terminal pathway), at the time of routine endomyocardial biop sy in heart transplant recipients. Ten patients in the immediate posttransp lantation period (0-100 days) and 19 patients more than 6 months after tran splantation were studied. Results, No correlation was found between plasma levels of complement activ ation fragments and the presence of biopsy-proven acute allograft rejection or AG;A (assessed by coronary angiography), However, plasma C4d and SC5b-9 were significantly elevated in 9 of 10 and 7 of 10 patients, respectively, in the immediate posttransplantation period, This was followed by progress ive decrease in the levels of C4d and SC5b-9 fragments during the first 4-6 weeks after transplantation. Conclusion, We conclude that measuring plasma levels of fragments C4d and S C5b-9 is not a useful noninvasive method for detecting acute rejection or A GA after heart transplantation However, this study provides further evidenc e that early complement activation after heart transplantation may play a p athogenic role in allograft injury.