Pathogenic Immunoglobulin M (IgM) (IgM)

Pathogenic Immunoglobulin M (IgM) refers to IgM antibodies that directly contribute to disease pathology through autoantibody activity, complement activation, or physical properties like hyperviscosity (Janeway's Immunobiology, 2017). As a large pentameric molecule, IgM is the most potent activator of the classical complement pathway, which in pathological contexts leads to conditions such as Cold Agglutinin Disease (CAD) where IgM binds to red blood cells and triggers hemolysis (Röth et al., 2021). It is also the primary driver of Waldenström's Macroglobulinemia, where excessive monoclonal IgM production causes blood hyperviscosity and organ damage (Gertz, 2021). Therapeutic interventions typically target the B-cells or plasma cells responsible for IgM secretion, or inhibit the downstream complement cascade initiated by the pathogenic pentamers (FDA, 2022). Management of pathogenic IgM is critical in treating various autoimmune neuropathies and hematological malignancies where these antibodies serve as both the driver of disease and a primary biomarker for monitoring treatment efficacy (Dalakas, 2019).

Other names

Monoclonal IgMCold AgglutininAutoimmune IgMPentameric IgMM-proteinParaprotein

Therapeutic strategies include the depletion of B-lymphocytes and plasma cells to reduce IgM production, the inhibition of the classical complement pathway (e.g., C1s inhibition) to prevent IgM-mediated hemolysis, and the physical removal of IgM from circulation via plasmapheresis or immunoadsorption.