The paradox of cytokine monitoring-predictor of immunologic activity as well as immunologic silence following cardiac transplantation.

The utility of cytokine monitoring to predict the onset of significant rejection was evaluated in 34 patients following heart transplantation. Serial blood levels of 5 cytokines involved in inflammation and immune activation(IL-1, IL-2, IL-6, IL-8, and TNF) were correlated with clinical outcome and endomyocardial biopsy scores. The majority of patients (68%) experienced a significant rejection during the study period. IL-6 and IL-8 levels were effective markers of significant rejection 2-4 days before diagnosis with EMBX. IL-6 and IL-8 levels of 15 and 1000 pg/ml predicted the onset of rejection with sensitivities of 75% and 66% and specificities of 86% and 76%, respectively. In contrast, IL-6 and IL-8 levels less than 15 and 400 pg/ml predicted a rejection-free course with sensitivities of 91% and 91% and specificities of 81% and 68%, respectively. The remaining cytokines differentiated patients experiencing a clinically unremarkable course from those experiencing mild-to-moderate rejection but did not discriminate rejection severity. IL-6 levels identified steroid and OKT3 resistance within 48 hr of antirejection therapy. IL-6 levels elevated to 197 +/- 20 pg/ml among steroid-resistant patients and normalized to 20 +/- 5 pg/ml among responders. IL-8 levels delineated OKT3 resistance. IL-8 levels rose to 3496 +/- 500 pg/ml among nonresponders, whereas levels fell to 152 +/- 50 pg/ml among responders. This study demonstrates that IL-6 and IL-8 are useful markers of rejection and therapeutic efficacy following heart transplation.