In order to investigate locally produced mediators during the process of organ storage in liver transplantation, we collected the liver preservation solution effluent of 15 transplanted livers and compared it with serum samples taken preoperatively from donor and recipient, as well as 60 min after reperfusion. The mean ischemia time +/- SEM was 10 h 10 min +/- 53 min. Mean concentrations in University of Wisconsin preservation solution effluent were: interleukin-(IL-)1beta 154 +/- 77 pg/ml; IL-1 receptor antagonist (IL-1 ra) 1281 +/- 309 pg/ml; IL-6 412 +/- 90 pg/ml; and for tumor necrosis factor-(TNF-)alpha 74 +/- 21 pg/ml. Cytokine levels in the donors were lower than those detected in the effluent. All measured cytokines showed higher concentrations in the effluent compared to those of the recipient prior to the operation. With respect to a comparison of donor and recipient values, no correlation is evident. Likewise, the ischemic time does not correlate with effluent values. Further development of liver preservation concepts requires information about the state of the graft before reperfusion. Data on cytokine liberation may serve as a helpful tool for the further development of preservation concepts because they enable an estimation of cell activation during preservation.