Amylase in duodenal aspirates: relationship between concentration, activity and isoenzyme pattern

Concentrations of immunoreactive amylase, catalytic activities, and isoenzyme patterns were compared in 220 duodenal aspirates from 205 patients suspected of pancreatic disease. Immunoreactive amylase was measured in an ELISA assay, employing rabbit antibodies raised against a highly purified human pancreatic amylase. Generally, the 220 duodenal aspirates showed a linear relationship between catalytic activity and concentration. Twenty-five of the 220 samples contained the slowly migrating form of pancreatic amylase, caused by heterozygosis of the Amy-2 locus. This phenomenon did not influence the relation considered. Thirty-two of the 220 aspirates contained more than 20% non-pancreatic amylase. The concentration of immunoreactive amylase in these samples corresponded to that expected from their isoenzyme composition.