Serum protease inhibitor capacity for elastase and the severity of pancreatitis

To clarify the relationship between the diminution of the serum protease inhibitor capacity and the severity of pancreatitis, the binding capacity of serum protease inhibitors for exogenous elastase 1 (E1) was investigated by gel filtration, the elastase activity of the alpha 2-macroglobulin (alpha 2-M)-elastase complex was measured, and the relationship between these findings and the severity of pancreatitis was studied in 13 patients with pancreatic disease and 6 healthy subjects. When 125I-labeled E1 was added to the sera of healthy subjects, it bound to alpha 2-M and alpha 1-protease inhibitor (alpha 1-PI) with a mean ratio of 72:28. In mild acute pancreatitis (n = 5), the binding capacity of alpha 2-M was less than that in healthy subjects. In severe pancreatitis (n = 4), most of the exogenous E1 bound to alpha 1-PI (alpha 2-M vs. alpha 1-PI, 13:87). This diminution in the binding capacity of alpha 2-M correlated well with the severity of acute pancreatitis. In the sera of patients (n = 4) with pancreatic cancer containing much immunoreactive E1, the proportion of exogenous E1 bound by alpha 2-M and alpha 1-PI (25:75) was similar to that seen in severe acute pancreatitis. A significant inverse relationship between the binding capacity of alpha 2-M and the activity of the endogenous elastase bound to alpha 2-M was seen in various pancreatic diseases.(ABSTRACT TRUNCATED AT 250 WORDS)