Category: 

What Is Beta-2 Microglobulin?

Article Details
  • Written By: Valerie Clark
  • Edited By: Angela B.
  • Last Modified Date: 02 September 2016
  • Copyright Protected:
    2003-2016
    Conjecture Corporation
  • Print this Article
Free Widgets for your Site/Blog
In late 19th-century London, mail was delivered to residential addresses up to twelve times each day.   more...

September 28 ,  1924 :  Two US military planes complete the first flights around the world.  more...

Beta-2 microglobulin (b2m) is a naturally occurring protein in the human body. It is one of two polypeptide chains that make up the structure of a major histocompatibility complex (MHC) Class I molecule. Certain characteristics of b2m make it suitable for detecting tumor cells, especially in blood and kidney cells. B2m also has been used to evaluate kidney function following a kidney transplant operation, and as a prognostic tool for immune system-related diseases.

This large protein belongs to a class of histocompatibility molecules, which are glycoproteins expressed at the surface of nucleated white blood cells in vertebrates. MHC Class I molecules such as b2m are useful for detecting incompatible or genetically different cells within the body. Some key characteristics of beta-2 microglobulin are that it has no transmembrane region, associates with the alpha chain of MHC Class I molecules by non-covalent bonds and associates with the human hemochromatosis (HFE) protein. Normal levels of beta-2 microglobulin range from 1 to 2.1 micrograms per milliliter (µg/mL); upper normal range values are 2.0 to 2.5 µg/mL.

Ad

An MHC Class I molecule consists of two polypeptide chains, a long alpha chain on the left and a shorter chain on the right that is beta-2 microglobulin. Histocompatibility molecules also are referred to as antigens because of their ability to elicit an immune system response. Basically, for a tissue transplant to be successful, the MHC of the tissue’s cells must be compatible between the donor and the recipient. Additionally, if an unhealthy cell containing foreign material from a disease, virus or bacteria is detected, then the MHC Class I molecules will flag them as a signal for the immune system to attack the cells containing foreign proteins. In clinical studies, the level of beta-2 microglobulin production is directly associated with lymphocyte activation, a signature immune system response.

B2m molecules have been targeted in cancer treatment and immune system disorders in which T-cells are involved. Clinical studies with b2m-deficient mice have demonstrated an important role of beta-2 microglobulin in cellular surface expression of MHC Class I molecules and peptide binding. Without peptide binding and subsequent protein synthesis, the production of certain immune system-related cells, including T-cells, is halted when b2m is absent. Immunology assays have been developed using b2m as a tumor marker.

A physician or oncologist may perform a b2m test to get a general idea of how much cancer may be present in a patient. Elevated b2m levels can indicate multiple myeloma, lymphoma or leukemia. Both blood and urine tests for beta-2 microglobulin have been used for patients with kidney disease following a kidney transplant. B2m can distinguish between glomular and tubular kidney disorders. In rare cases, b2m tests are used to evaluate the effects of a disease on the central nervous system.

Ad

You might also Like

Recommended

Discuss this Article

Post your comments

exception 'Exception' with message 'error writing captcha: Duplicate entry '2147483647' for key 'PRIMARY'' in /ssd/www/wisegeek/public_html/_core/classes/public/Captcha.php:44
Stack trace:
#0 /ssd/www/wisegeek/public_html/_core/controls/public/ControlDiscussionPostBox.php(324): Captcha->createCaptcha()
#1 /ssd/www/wisegeek/public_html/framework/classes/Control.php(104): ControlDiscussionPostBox->preRender(false)
#2 /ssd/www/wisegeek/public_html/framework/classes/Control.php(149): Control->render()
#3 /ssd/www/wisegeek/public_html/tpl/default-nocustom-lu/pages/public/article/article.htm(526): Control->__toString()
#4 /ssd/www/wisegeek/public_html/framework/classes/Control.php(300): require('/ssd/www/wisege...')
#5 /ssd/www/wisegeek/public_html/framework/classes/Control.php(309): Control->requireTpl('pages/public/ar...', Object(PageArticleCom), true)
#6 /ssd/www/wisegeek/public_html/framework/classes/Control.php(131): Control->renderTpl('pages/public/ar...', Object(PageArticleCom))
#7 /ssd/www/wisegeek/public_html/framework/classes/FormDataControl.php(87): Control->renderTemplate()
#8 /ssd/www/wisegeek/public_html/framework/classes/Control.php(109): FormDataControl->renderTemplate()
#9 /ssd/www/wisegeek/public_html/framework/classes/ScriptPage.php(50): Control->render(false)
#10 /ssd/www/wisegeek/public_html/framework/classes/Control.php(149): ScriptPage->render()
#11 /ssd/www/wisegeek/public_html/framework/classes/Page.php(97): Control->__toString()
#12 /ssd/www/wisegeek/public_html/_core/classes/public/PublicFrontController.php(443): Page->processRequest()
#13 /ssd/www/wisegeek/public_html/_core/classes/public/PublicFrontController.php(7): PublicFrontController->renderPage()
#14 /ssd/www/wisegeek/public_html/index.php(11): PublicFrontController::run()
#15 {main}