Proteases present in some pancreatic cyst fluids may affect mucin immunoassay by degrading antibodies and antigens.

Objectives: Biomarker detection in pancreatic cyst fluids is of importance to improve the diagnosis of mucinous cystadenoma, a precancerous lesion. However, assay protocols are generally established for serum testing.

Methods: Immunoradiometric assay of gastric M1/MUC5AC mucin was performed on pancreatic cyst fluids with well-characterized monoclonal antibodies.