IgMrelated

IgM-related is a broad term used to describe conditions and processes linked to immunoglobulin M (IgM). IgM is the first antibody produced during an immune response and is typically found in the blood as a pentamer. It plays a key role in initial defense against pathogens, efficiently activating the classical complement pathway and promoting agglutination of microbes. Because of its structure, IgM has high avidity but relatively low affinity.

In clinical practice, “IgM-related” may refer to disorders of IgM production or function. IgM deficiency leads to increased susceptibility to infections, particularly with encapsulated bacteria. Conversely, abnormalities in IgM production can be seen in IgM-secreting disorders such as certain monoclonal gammopathies.

Several well-described IgM-related diseases involve pathogenic IgM antibodies or monoclonal IgM proteins. Waldenström macroglobulinemia is a lymphoplasmacytic lymphoma characterized by an IgM-secreting clone and may cause hyperviscosity, visual symptoms, or neuropathy. Cryoglobulinemia can involve IgM-containing immune complexes that precipitate in cold temperatures, causing vasculitic symptoms. Cold agglutinin disease is mediated by IgM antibodies that agglutinate red cells at low temperatures, leading to hemolysis. IgM autoantibodies are also observed in various autoimmune conditions, sometimes contributing to disease manifestations.

Diagnosis typically relies on serum immunoglobulin quantification and electrophoresis, IgM-specific serologic tests, and assessment for related diseases. Management depends on the underlying condition and may include infection prevention, plasmapheresis for hyperviscosity, immunochemotherapy, or targeted therapies for malignant IgM-producing clones.

See also Immunoglobulin M, Waldenström macroglobulinemia, cryoglobulinemia, cold agglutinin disease.