Radioimmunoassay of human pancreatic amylase with monoclonal antibody.

A monoclonal antibody (E-21) was obtained that specifically binds to human pancreatic amylase and shows negligible cross-reaction with human salivary amylase. Using this antibody a radioimmunoassay was developed for pancreatic amylase in human serum. The assay was shown to be sensitive (detectable up to 7 mg/L), reproducible, and specific for pancreatic amylase. In normal subjects, the mean concentration of serum pancreatic amylase determined by this method was 36.3 mg/L with a 95% confidence range of 16.5 to 79.2 mg/L. A good correlation was observed between the concentrations of immunoreactive pancreatic amylase (IR-PA) and enzymatic activities in 20 serum samples (r = 0.97). The concentration of serum IR-PA was below the detectable limit in pancreatectomised patients, and was greatly increased in patients with acute pancreatitis; the latter was accompanied by parallel changes in total enzymic activity. In patients with mumps, the serum IR-PA level was within the normal range whereas the total enzymic activity was elevated.