<正> OBJECTIVES: To evaluate the behavior of serum interleukin 10 (IL-10) in patients with acutepancreatitis and to explore the relationship between this cytokine and the severity of the disease.METHODS: In 45 patients with acute pancreatitis, the serum concentrations of IL-10 was determinedon days 1, 2, 3, 4, 5 after admission. Twelve healthy subjects were also studied as controls. Thesesubjects were tested using a commercial ELISA kit. The severity of pancreatitis was determined accordingto APACHE Ⅱ score and Balthazar CT criteria.RESULTS: Healthy subjects had no detectable serum levels of IL-10. In acute pancreatitis patients,the serum IL-10 levels were increased on the first day after the onset of the disease and then progressivelydecreased in the following days. On the first day after the onset of acute pancreatitis, the serum levelsof IL-10 in patients with mild acute pancreatitis were significantly higher than in those with severe acutepancreatitis. In the following days, however, no statistically significant difference was observed betweenthe two groups.CONCLUSIONS: Serum IL-10 concentration reflects the severity of acute pancreatitis. IL-10 is a usefulvariable for early prediction of the prognosis of acute pancreatitis. The low values of serum IL-10 inpatients with severe acute pancreatitis suggests that there may be altered down-regulation of immunesystem response. An enhanced release of IL-10 may be a method for early treatment of acute pancreatitis.