ObjectiveTo determine changes in the production of inflammatory cytokines and acute-phase proteins, and in the priming of peripheral blood mononuclear cells (PBMC), as mechanisms for the high incidence of postoperative complications in patients who have undergone hepatectomy simultaneously with resection of the gastrointestinal tract.DesignProspective, clinical study for 3 wks after operation.SettingA surgical department in a university hospital.PatientsTwenty-one consecutive adult patients with synchronous and metachronous hepatic metastases from gastrointestinal malignancies, curatively resected by simultaneous resection (group A, n = 9) or by hepatectomy alone (group B, n = 12), and 15 patients with gastrointestinal malignancies undergoing curative resection (group C).InterventionPeripheral venous blood samples collected before operation and on days 1, 3, 5, 7, 10, 14, and 21 after operation.Measurements and Main ResultsThe serum and plasma levels of acute-phase proteins, interleukin (IL)-1 beta, IL-6, tumor necrosis factor (TNF)-alpha, and endotoxin were measured. The in vitro production of IL-1 beta and TNF-alpha by PBMC was also determined by the stimulation of lipopolysaccharide. The incidence of postoperative complications was significantly higher in group A than in groups B and C. The serum levels of IL-6 increased significantly, with a peak at postoperative day 1 in all groups, and the peak levels of IL-6 in groups A and B were significantly higher than that in group C. The serum levels of all acute-phase proteins measured in this study (alpha1-antitrypsin, haptoglobin, and C-reactive protein) increased markedly after operation in group C (p < .05). In group A, only C-reactive protein increased after operation, but its peak level was lower than in groups B and C (p < .05). Although IL-1 beta and TNF-alpha in the serum were not detectable in any of the groups during the entire study period, the lipopolysaccharide-induced in vitro production of IL-1 beta and TNF-alpha by PBMC in all groups was significantly elevated after operation, with a peak at days 1 and 3 after operation, respectively. In addition, the elevation of the in vitro production of IL-1 beta and TNF-alpha in group A was significantly greater than that in group C, lasting until postoperative day 5 (IL-1 beta) and postoperative day 10 (TNF-alpha). The levels of plasma endotoxin increased significantly in all groups, with a peak at day 1 after operation, and the peak levels were significantly higher in group A than in groups B and C. There was a significant correlation between the peak levels of in vitro TNF-alpha production and the peak levels of plasma endotoxin (r2= .331, p < .01).ConclusionsThe augmented enhancement of the priming of PBMC as a result of surgery in patients undergoing simultaneous resection of the liver and gastrointestinal tract, together with the reduced synthesis of the acute-phase reactants and impaired host defense mechanisms, might be responsible for the high incidence of postoperative complications, possibly because subsequent exposure of primed macrophages/monocytes to triggering substances such as endotoxin and bacterial components after operation results in inappropriate production of inflammatory cytokines. (Crit Care Med 1999; 27:929-936)