Multicenter evaluation of a specific pancreatic isoamylase assay based on a double monoclonal-antibody technique.

Abstract

Eleven evaluators from nine laboratories in five countries evaluated a new immunoinhibition method for pancreatic isoamylase determination that is as simple to perform as that for total amylase. The precision at low and intermediate activity concentrations was superior, and at high concentrations it equalled that of the wheat-germ inhibitor method. The test was linear to approximately 2000 U/L, depending on the instrumentation used. The percentage salivary isoamylase activities remaining in specimens after reaction with two monoclonal antibodies ranged from 2 to 4.4%. Comparative studies showed good correlation with the wheat-germ inhibitor (r greater than 0.978) and electrophoresis methods (r = 0.920). Hemolysis, lipemia, and bilirubinemia have no effect on results. Interlaboratory studies demonstrated excellent transferability of the method, if instruments are calibrated with the same calibrator. Reference intervals for pancreatic isoamylase are 13 to 64 U/L (25 degrees C), 13 to 83 U/L (30 degrees C), and 17 to 115 U/L (37 degrees C). A clinical evaluation of patients with acute pancreatitis showed that pancreatic isoamylase has a greater clinical sensitivity than total amylase.

Lipase and Pancreatic Amylase Activities in Tissues and in Patients with Hyperamylasemia

“…Pancreatic isoamylase was determined on a Cobas-Bio (Roche Diagnostic Systems, Montclair, NJ) using the Boehringer Mannheim (Indianapolis, IN) enzymatic colorimetric test, pancreatic alpha-amylase p-nitrophenylmalthoheptaoside. 9 In this assay, the activity of human salivary isoamylase is inhibited by a monoclonal antibody that does not affect pancreatic isoamylase. The activity of pancreatic isoamylase is then measured at 37°C using a p-nitrophenyl-D-maltopeptaoside substrate.…”

A Case of a Composite Adrenal Medullary Tumor of Pheochromocytoma and Ganglioneuroma Masquerading as Acute Pancreatitis

“…We did not perform an analysis of amylase isoenzyme by the electrophoretic method, but pancreatic amylase, not total amylase, was assayed by a enzymatic photometric test, which is based on the method of monoclonal antibodies to inhibit the salivary enzyme and which distinguish pancreatic and salivary amylase sufficiently 17 , 18) . Therefore, it could be suggested that the pancreatitis was caused by the pheochromocytoma in our case.…”

Validation of determination of human α-amylase activity for patients with pancreatic diseas

“…В качестве биоматериала использовали 73 обезличенных образца сыворотки крови с различной активностью и изоферментным составом α-амилазы, которые были получены от доноров и хранились не более 14 дней при температуре -20 °С [18]. Степень ингибирования слюнной α-амилазы оценивали с применением образцов препаратов слюнной α-амилазы (Sigma, США) [19]. Для уточнения линейного диапазона измерения активности фермента реагентами с GalG 2 CNP использовали препарат α-амилазы «α-amylase from hog pancreas» (Fluka, Швейцария) с начальной общей активностью 46,4 кЕД/л.…”