Introduction Human Immunoglobulin M (IgM) is a large mushroom-shaped antibody against A and B antigens on red blood cells and is produced by B cells (1). It forms a pentamer or a hexamer in serum and also a monomer on B cell surface. Each of the five monomers has a molecular mass of 180 kDa, consists of two light and two heavy chains, and a joining J chain required for the synthesis of the pentamer (2 - 3). Upon an exposure to an acute infection, IgM is the predominant antibody produced to fight the foreign red blood cell antigen. It activates complement and agglutinates red blood cells. IgM is the first immunoglobulin made by the fetus and by B cells when stimulated by antigens (4 - 5). It does not pass across the human placenta due to its large size. Elevated IgM indicates viral hepatitis infection and primary biliary cirrhosis (6 - 8). IgM is a useful tool in the diagnosis of infectious diseases.
Principle of the Assay The AssayMax Human Immunoglobulin M (IgM) ELISA kit is designed for detection of human IgM in plasma, serum, urine, saliva, milk, and cell culture samples. This assay employs a quantitative sandwich enzyme immunoassay technique that measures human IgM in less than 4 hours. A polyclonal antibody specific for human IgM has been pre-coated onto a 96-well microplate with removable strips. IgM in standards and samples is sandwiched by the immobilized polyclonal antibody and biotinylated polyclonal antibody specific for human IgM, which is recognized by a streptavidin-peroxidase conjugate. All unbound material is then washed away and a peroxidase enzyme substrate is added. The color development is stopped and the intensity of the color is measured.