Beta 2 Microglobulin Test

Beta 2-microglobulin test, also known as the B2M test is an effective tumor marking diagnostic investigation. Beta 2 Microglobulin is a protein that is found in the cell membrane. Beta 2 Microglobulin predominantly associates with heavy chains of the immunoglobulin belonging to the major histocompatibility (condition in which the cells of one tissue can survive in the presence of cells of another tissue) cells of class I origin. The class I antigens are expressed in the lymphoid cells. Hence these antigens are called classic transplantation antigens. Beta 2 microglobulins are remarkable with respect to initiating cellular immunity. Their small size (11,500 Daltons) allows them to pass through the glomerulus during the process of renal filtration.

Clinical manifestations associated with the beta 2-microglobulin factors are predominantly associated with vital organ functionalities. It also paves the way to analyze the presence of tumors especially in case of myelomas. It is also used as an effective prognostic marker in case of malignancies such as leukemia. Raised beta microglobulin levels indicate the presence of disorders pertaining to kidneys, which is a primary indication of renal failure. The reference range in case of serum is microgram/ ml and in case of urine specimen, it is 0.3 microgram per ml. Many oncologists prefer to request the B2M test in order to rule out the severity of metastases in case of conditions like multiple myeloma.

Central nervous system involvement can also be analyzed by estimating the B2M values. In multiple myelomas, the proliferation of B2M occurs at a minimum level at the first stage, and as the stage proceeds the serum values of the B2M values rise to a larger extent. This indicates the body's inability to identify the foreign cells leading to immune system associated cellular disorders like cancers. The class I antigens which serve as the surface recognition cells help in identifying the foreign cells and the B2M test is very essential.

Clinical studies on this respective protein affirms its importance as independent predictor of the asymptomatic multiple myeloma. B2M investigations along with other indicators can be an effective prognostic tool in identifying and diagnosing multiple myelomas of different kinds. With respect to central nervous system involvement, elevated cerebrospinal fluid also indicates rise in B2M values. In addition to these classical conditions, B2M values are elevated in autoimmune disorders and viral infections especially in Cytomegalo virus.

The significance of B2M analysis

Malignancy: Indicator for the onset of chronic lymphocytic leukemia and multiple myeloma.

Waldenstorm macroglobulinemia: In this condition the B2M is an effective indicator to rule out the presence of myeloid-dysplastic syndromes.

HIV:Inverse correlations of B2M are significant in relation with CD4+ T-lymphocyte cells indicating disease progression.

Neurological involvement: In conditions such as sarcoidosis, dementia and meningitis, elevated CSF and B2M levels are significant markers.

Rheumatologic involvement: Studies indicate the presence of B2M deposits in higher amounts in the joints indicate rheumatologic association of the respective protein molecule.