LeLISA: a new lectin-based immunoassay for evaluation of mucins and pancreatic cystic lesions (PCL)

Abstract

Background The discrimination of mucinous from serous pancreatic cysts and pseudocysts is an important clinical issue. We established an assay to detect different types of carbohydrate containing molecules like glycans and mucins in biological materials and have called it the LeLISA. The method implies a certain specificity since different lectins bind predominantly to certain di -or oligosaccharides that may appear typically on certain cell types or, as a consequence of cell transformations often called aberrant mucin expression. The presence, or absence of reactivity with some lectins may be associated with different pathological conditions and may therefore have diagnostic implications, for instance in differentiation of pancreatic cysts. We aimed at detecting mucin-calprotectin (Cp)complexes (Muc/Cp) bound to lectin (Le) coated wells using enzyme labelled anti-Cp.Materials and methods The LeLISA is a special type of ELISA where the catching antibody is replaced by a Le. Eight different randomly selected lectins were used for coating of microwells and subsequently incubated with pancreatic cyst fluids collected via endoscopic ultrasound fine needle aspiration (EUS-FNA) from patients with mucinous, serous cysts and pseudocysts, 10 patients in each group. The diagnosis was confirmed through histopathological examination of surgical specimens and follow-up after initial diagnosis. The binding of Muc/Cp to lectins was demonstrated by a new type of ELISA where cyst fluids were incubated in microwells coated with different types of lectins followed by enzyme (HRP) labelled monoclonal anti-Cp. The name LeLISA was introduced for this new procedure.Results Muc/Cpin cyst fluids bound to several of the eight lectins tested, in particular to Galanthus nivalis, Agaricus blazei Murill and Phaseolus vulgaris. This was especially noticeable for fluids from mucin-producing cysts.Conclusions Cyst fluids contain complexes with Cp and mucins. The LeLISA may be a new method for detection of aberrant mucin expression and possibly a way of discriminating between different types of pancreatic cysts, in particular when the Galanthus lectin and enzyme labelled anti-Cp monoclonals are used. The binding to lectins depends upon certain carbohydrate sequences recognized by the individual lectin.