Beta2-microglobulin$$

Plasma protein from the beta globulin fraction, which is found in the membranes of all cells and is secreted into various body fluids (e.g. serum, urine, cerebrospinal fluid). The protein is encoded by the B2M gene (B2M stands for "beta-2-microglobulin"), which is located on chromosome 15q21.1.

Functionally, this protein forms the extracellular portion MHC-I complex and plays an important role in the presentation of exogenous antigens. In urine, it serves as a marker for tubular proteinuria.

Standard values:

• Newborns up to the 3rd month 2.8-3.4 mg/l; from the 3rd month to the 1st year of life 1.8-2.2 mg/l
• Children 1,4-1,6 mg/l
• Adults 0.8-2.4 mg/l
• Adults from 60.LJ <3.0 mg/l
• Conc. in urine: up to 0.3 mg/l

Pathological serum concentrations:

• Versch. Lymphoma: chronic lymphocytic leukemia (CLL), Hodgkin's disease, non-Hodgkin's lymphoma, plasmocytoma, immunocytoma (prognostic parameter).
• MGUS: elevated beta-2-microglobulin in serum is an indication of malignancy.
• Renal disease: beta-2-microglobulin is elevated by a factor of 10-50 in impaired glomerular filtration rate (GFR) in renal insufficiency.
• HIV infection: at beta-2-microglobulin levels in serum >5.0 mg/l there is a high risk of developing AIDS within 3 years!
• Dialysis: leads to beta-2-microglobulin-associated amyloidosis (E85.3). Amyloid consists of intact beta-2 microfibrils. Vision (carpal tunnel syndrome), articular cartilage and skin are affected.

1. Nkuipou-Kenfack E et al (2015) Identification of ageing-associated naturally occurring peptides in human urine. Oncotarget 27: 106-117
2. Xue W et al (2015) Clinical characteristics and prognostic factors of patients with mature T-cell lymphoid malignancies: a single-institution study of 225 cases. Front Med 9: 468-477