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)