IgM (Immunoglobulin M)
Pathogenic paraprotein causing end-organ damage
- Expression
- Elevated (monoclonal)
- Evidence level
- established
Role in pathogenesis
Monoclonal IgM is the effector molecule responsible for most WM complications. Its large pentameric structure causes hyperviscosity. Anti-MAG IgM causes neuropathy. IgM can also form cryoglobulins, cold agglutinins, or deposit as amyloid. IgM level is a treatment response marker.