Proteins are made from amino acids and are important constituents of all cells and tissues. There are many different kinds of proteins in the body with many different functions, [for example, enzymes, some hormones,hemoglobin, LDL, fibrinogen, collagen and immunoglobulins].
Serum proteins are separated by electrophoresis into albumin and globulins.
Albumin is the protein of highest concentration in the serum. It carries many small molecules, but is also of prime importance in maintaining the oncotic pressure of the blood .
Globulins are roughly divided into alpha-1, alpha-2, beta ( β1 and β2), and gamma globulins. These can be separated and quantitated in the laboratory by electrophoresis and densitometry.
The alpha-1 fraction includes alpha-1 anti-trypsin and thyroxine binding globulin. The alpha-2 fraction contains haptoglobin, ceruloplasmin, HDL and alpha-2 macroglobulin.Generally, alpha-1 and alpha-2 proteins levels increase in the presence of inflammation.
The beta fraction includes transferrin, plasminogen, and beta-lipoproteins. The gamma fraction includes the various types of antibodies (immunoglobulins M, G, and A).
The electrophoresis technique is the only reliable way of detecting a paraprotein in biological fluids, and also is the initial screening procedure and therefore should have sufficient resolution to do this adequately. It is a clinical significant method for detecting serum protein changes associated with certain diseases. Changes from normal serum protein patterns, either as the presence of extra components (monoclonal bands),(frequency) or as an increase of normal occurring components, alerts the clinician to perform further protein analysis.
Electrophoresis roughly measures the various types of protein in the serum portion of a blood sample.Individual proteins, with the exception of albumin are not usually measured by electrophoresis. However,protein fractions or groups are measured. The levels of protein fractions can be roughly measured by measuring the total serum protein and multiplying by the relative percentage of each component protein fraction, or automatically by HellabioScan.
Serum electrophoresis should always be accompanied by measurement of serum IgG, IgA and IgM concentrations. Samples with raised IgA and IgM concentrations that cannot be confirmed as polyclonal by the electrophoresis pattern should be analysed by immunofixation to exclude small paraprotein bands obscured by one of the normal zones
Electrophoresis on Agarose gel is the most common method currently in use in clinical diagnostic for the detection of paraproteins in serum and urine.
The clinical use of electrophoresis in protein analysis is generally based on the simple electrophoretic separation of proteins according to their relative mobility and molecular weight.
Serum Protein electrophoresis can be applied in a variety of clinical cases such as:
¨ In cases in which multiple myeloma, macroglobulinemia, or amyloidosis is suspected.
¨ In any cases of unexplained weakness or fatigue, anemia, elevation of the erythrocyte sedimentation’s rate, back pain, osteoporosis or osteolytic lesion, immunoglobulin deficiency, hypocalcaemia, Bence Jones proteinuria, renal insufficiency or recurrent infections.
¨ In peripheral neuropathy, carpal tunnel syndrome, refractory congestive heart failure, nephrotic syndrome, orthostatic hypertension or malabsorption.