IgM detection via selective recognition by mannose-binding protein

Ca(2+)-dependent mannose-binding proteins (MBPs) belong to the family of animal lectins isolated from the liver and serum of rabbits, humans and rodents. They perform in vivo as defense molecules that act as opsonins by enhancing the clearance of mannose-rich pathogens and have been used in vitro for the purification of immunoglobulin M (IgM). In this study, we used MBPs as a sensitive and specific reagent for the detection of IgM due to their high specificity for mannose found only in IgM carbohydrate regions. MBP performed as a sensitive alternative to the usually used anti-IgM, where very low concentrations of IgM should be detected. IgM plays a central role in the initial response of the immune system to the invasion of foreign pathogens, as the early detection of the appearance of pathogenic IgM in biological fluids is of great significance in the diagnosis and treatment of many acute pathological cases. The development of a highly sensitive and reliable assay for the detection of low concentrations of IgM based on covalent binding on epoxy film-coated surfaces and selective recognition of IgM by MBP may be of clinical importance.