To determine to what extent cardiac allograft transplantation induces the production of heartreactive antibody or antibodies (HRA), we assayed pre- and postoperative sera from 68 cardiac transplant recipients. During the first postoperative month, HRA was detected in 63% of transplant patients, but in only 25% of 40 cardiac surgical controls (p < 0.01). The incidence of detectable preoperative HRA did not differ in the two groups (13% transplant vs 10% nontransplant patients).
To evaluate whether HRA may serve as a monitor of cardiac rejection, we further analyzed sera during 90 episodes of rejection in 65 patients, as diagnosed by endomyocardial biopsy. HRA was present in 65% of first rejection episodes, 62% of all episodes, and in at least one episode in 69% of patients rejecting. HRA generally rose before initial rejection, peaked near rejection, and decreased gradually with rejection therapy. In many patients, HRA appeared to be an early signal of posttransplant immune activation. A relatively neutral role for circulating HRA with respect to clinical outcome was suggested.
We conclude that HRA appears after cardiac transplantation, despite immunosuppression, in a frequency and intensity too great to be explained on the basis of pericardiotomy alone. Because HRA does not appear in all transplant patients during rejection episodes, a rising HRA titer cannot be used as a sole clinical indicator of impending rejection