A serum marker that correlates with tumor burden and stage of disease in CLL, multiple myeloma and Waldenstrom’s macroglobulinemia.
Elevated levels are a predictor of survival.
β2 microglobulin also known as B2M.
It is a component of MHC class I molecules.
MHC class I molecules have α1, α2, and α3 proteins which are present on all nucleated cells. and that would exclude red blood cells.
The β2 microglobulin protein is encoded by the B2M gene.
Gene location Chromosome 15 Band 15q21.1
β2 microglobulin associates not only with the alpha chain of MHC class I molecules, but also with class I-like molecules such as CD1 and Qa.
It is associated with the HFE protein, regulating the expression of hepcidin in the liver.
Hepcidin targets the iron transporter f2242oportin on the cytoplasmic membrane of enterocytes and macrophages for degradation resulting in increased iron uptake from food and decreased iron release from recycled red blood cells in the mononuclear phagocyte system, respectively.
Loss of this function causes iron excess and hemochromatosis.
In patients on long-term hemodialysis, it can aggregate into amyloid fibers that deposit in joint spaces, causing a disease, known as dialysis-related amyloidosis.
Low levels of β2 microglobulin can indicate non-progression of HIV.
Levels of β2 microglobulin can be elevated in multiple myeloma and lymphoma, though primary amyloidosis and secondary amyloidosis are more common.
The normal value of β2 microglobulin is <2 mg/L.