Cell free serum interleukin-2 receptor levels after heart transplantation.

The aim of this study was to predict episodes of rejection or infection in heart transplant recipients by monitoring serum interleukin-2 receptor (IL-2R) levels, rather than by endomyocardial biopsy. The shedding of IL-2R from activated lymphocytes results in increased serum interleukin-2 levels and is probably a result of immune activation occurring in both rejection and infection processes. As a group, heart transplant recipients who had no rejection of infection had significantly increased serum IL-2R levels compared with healthy controls. Patients who had moderate and severe rejection, and infection, had significantly increased serum IL-2R levels compared with levels in patients without rejection or infection. High serum IL-2R levels were seen mainly within the first 3 months after transplantation. Of 15 patients studied, nine had consistent increases in serum IL-2R levels with episodes of rejection or infection. Serum IL-2R levels did not correlate with serum cyclosporine levels. The monitoring of serum IL-2R levels was not a sensitive test of rejection because increases were not seen in all episodes of rejection; increases were seen, however, in all cases of infection. This test lacked specificity as serum IL-2R levels increased during episodes of both rejection and infection. In conclusion, the monitoring of serum IL-2R levels may be a useful way to routinely monitor or screen for possible rejection infection in heart transplant recipients, but this method should not replace endomyocardial biopsy for diagnosing rejection.