Radioimmunoassay of human pancreatic elastase 1. In vitro interaction of human pancreatic elastase 1 with serum protease inhibitors.

A radioimmunoassay for determination of human pancreatic elastase 1 was developed and the interaction of pancreatic elastase 1 with serum protease inhibitors (alpha 2-macroglobulin and alpha 1-antitrypsin) was investigated. Gel filtration studies showed that immunoreactive elastase 1 was present in serum and intact plasma as a complex with alpha 1-antitrypsin. Proelastase 1 in human pancreatic juice did not bind to protease inhibitors. But, after incubation with human serum or after activation with bovine trypsin, it was present as a complex with alpha 1-antitrypsin. The pancreatic elastase 1 content of the serum, measured by radioimmunoassay, was found to be influenced by the contents of both serum alpha 2-macroglobulin and alpha 1-antitrypsin. A significant inverse correlation was observed between the serum immunoreactive elastase 1 and alpha 2-macroglobulin contents in various hepatic diseases. The concentration of serum immunoreactive pancreatic elastase 1 was 1.79 +/- 0.62 ng/ml (mean +/- SD) in 28 normal controls. Its concentration was significantly increased in patients with acute pancreatitis, and although its concentration varied widely in patients with pancreatic cancer, its average concentration in these patients was significantly elevated.