Serum protein electrophoresis 290529 219574172 2008-06-15T22:13:53Z 41.208.64.255 /* Alpha-2 Zone */ [[Image:Electrophoresis.png|thumb|Schematic representation of a [[protein electrophoresis]] gel]] '''Serum protein electrophoresis''' is a laboratory test that examines specific proteins in the [[blood]] called [[globulins]]. Blood must first be collected, usually into an airtight vial or [[syringe]]. Electrophoresis is a laboratory technique where the blood serum (the fluid portion of the blood after the blood has clot) is placed on special paper treated with agarose gel and exposed to an [[electric current]] to separate the serum protein components into five classifications by size and electrical charge, those being [[serum albumin]], [[alpha-1-globulin]]s, [[alpha-2-globulin]]s, [[beta globulin]]s, and [[gamma globulin]]s. == Albumin == A fall of 30% is necessary before the decrease shows on electrophoresis. Usually a single band is seen. [[Heterozygous]] individuals may produce bisalbuminaemia - two equally staining bands, the product of two genes. Some variants give rise to a wide band or two bands of unequal intensity but '''none''' of these variants is associated with disease. Increased mobility results from the binding of [[bilirubin]], nonesterified [[fatty acids]], [[penicillin]] and [[acetylsalicylic acid]], and occasionally from tryptic digestion in acute [[pancreatitis]]. Absence of albumin is rare. This condition is called [[analbuminaemia]]. A decreased level of albumin, however, is common in many diseases and is especially important in [[liver disease]]. == Albumin - Alpha-1 Interzone == Even staining in this zone is due to alpha-1 lipoprotein ([[High density lipoprotein]] - HDL). Decrease occurs in severe inflammation, acute [[hepatitis]], and [[cirrhosis]]. Also, [[nephrotic syndrome]] can lead to decrease in albumin level; due to its loss in the urine through a damaged leaky [[glomerulus]]. An increase appears in severe alcoholics and in women during pregnancy and in puberty. The high levels of AFP that may occur in [[hepatomas]] may result in a sharp band between the albumin and the alpha-1 zone. == Alpha-1 Zone == [[Orosmucoid]] and [[antitrypsin]] migrate together but orosmucoid stains poorly so alpha-1 antitrypsin constitutes most of the alpha-1 band. Alpha-1 antitrypsin has an SG group and thiol compounds may be bound to the protein altering their mobility. A decreased band is seen in the deficiency state. It is decreased in the [[nephrotic syndrome]]{{Facts|date=February 2007}} and absence could indicate possible [[Alpha 1-antitrypsin]] deficiency. This eventually leads to [[emphysema]] from unregulated lung [[elastase]] breakdown by neutrophils in the lung tissue. [[Bence Jones protein]] may bind to and retard the alpha-1 band. == Alpha-1 - Alpha-2 Interzone == Two faint bands may be seen representing alpha-1 antichymotrypsin and [[vitamin D]] binding protein. These bands fuse and intensify in early inflammation due to an increase in alpha-1 antichymotrypsin, an [[acute phase protein]]. == Alpha-2 Zone == This zone consists principally of alpha-2 macroglobulin and haptoglobin. There are typically low levels in [[haemolytic anaemia]] (haptoglobin is a suicide molecule which binds with free [[haemoglobin]] released from [[red blood cells]] and these complexes are rapidly removed by [[phagocytes]]). Haptoglobin is raised as part of the acute phase response and therefore there is a typical increase in alpha-2 inflammation. A normal alpha-2 and a raised alpha-1 is typical in hepatic [[metastases]] and cirrhosis. Haptoglobin/haemaglobin complexes migrate more cathodally than haptoglobin as seen in the alpha-2 - beta interzone. This is typically seen as a broadening of the alpha-2 zone. Alpha-2 macroglobulin is raised in children and the elderly. This is seen as a sharp front to the alpha-2 band. It is of little diagnostic significance but is markedly raised in association with glomerular protein loss - the characteristic increased alpha-2 of the [[nephrotic syndrome]], due to its large size, cannot pass through glomeruli. Alpha-2 globulins can be raised in [[cirrhosis]], [[diabetes]], and [[malignancy]]. == Alpha-2 - Beta Interzone == Cold insoluble globulin forms a band here which is not seen in plasma because it is precipitated by [[heparin]]. There are low levels in inflammation and high levels in pregnancy. B lipoprotein forms an irregular [[crenated]] band in this zone. High levels are seen in type II [[hypercholesterolaemia]] and in the nephrotic syndrome. == Beta Zone == [[Transferrin]] comprises the beta-1 band. Increased beta-1 protein (due to the increased level of free transferrin) is typical of [[Iron deficiency anemia]], pregnancy, and [[Estrogen|oestrogen]] therapy. Beta-2 comprises C3 ([[Complement protein]] 3). It is raised in the acute phase response. == Gamma Zone == The [[immunoglobulins]] are the only proteins present in the normal gamma region. [[IgA]] has the most anodal mobility and migrates in the beta-gamma region. High levels give rise to beta/gamma fusion as in cirrhosis, [[respiratory infection]], [[skin disease]], or [[rheumatiod arthritis]]. IgA deficiency occurs in 1:500 of the population, as is suggested by a pallor in the gamma zone. Commonest causes of hypergammaglobulinaemia detected by electrophoresis are severe [[infection]], chronic liver disease, systemic [[lupus erythematosus]], and rheumatoid arthritis. Hypogammaglobulinaemia is easily identifiable. It is normal in infants. Zones or faint bands in the gamma region are often seen as a result of clones of immunoglobulins responding to antigenic challenge, e.g. in chronic [[hepatitis]] and chronic [[viral infections]]. [[C reactive protein]] can be seen as a faint band when the level is grossly abnormal, e.g. in [[Biological tissue|tissue]] damage. Dense narrow bands composing of immunoglobulins of a single class and containing only one type of [[light chain]] are known as [[paraproteins]] or M (monoclonal) proteins. IgA paraproteins migrate most anodally and may be confused with beta globulins. Paraproteins can arise from benign or malignant clones of [[B cells]] and their recognition and investigation is '''very''' important. [[Lysozyme]] may be seen as a band cathodal to the slowest gamma in myelomonocytic [[leukaemia]] in which it is released from [[tumour]] cells. [[Myeloma]] is the commonest cause of IgA and [[IgG]] paraproteinaemias but chronic lymphatic leukaemia and [[lymphosarcoma]] are not uncommon and usually give rise to [[IgM]] paraproteins. Waldenstrom's macroglobulinaemia, a malignant [[lymphoma]], also gives rise to an IgM paraprotein. Benign paraproteins are usually faint and do not show immunoparesis. Faint bands seen in the gamma region may be due to [[light chain disease]], particularly if there is immune peresis. [[Fibrinogen]] from [[Blood plasma|plasma]] samples will be seen in the fast gamma region. [[Category:Serology]] [[Category:Electrophoresis]] [[fr:Protéine sérique]]