Immunoglobulin M (IgM), along with IgA, IgD, and IgE, make up approximately 20% of the total gamma globulin in the body, with IgG accounting for the other 80%.Each class of antibody gets its designation from the heavy and light peptide chains that make up the antibody structure.IgM is the first immunoglobulin produced during the immune response and the first antibody produced in neonates. Serum levels of IgM are associated with certain autoimmune diseases, and abnormally low levels may indicate the presence of Wiskott-Aldrich Syndrome, an inherited immunodeficiency disorder. Monoclonal Anti-Human IgM is derived from the hybridoma1 produced by the fusion of mouse myeloma cells and splenocytes from an immunized mouse.