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Background
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All five immunoglobulin classes share the same basic four polypeptide chain structure of two heavy-chains and two light chains. There are five heavy chain types, and two light-chain types (Kappa and Lambda) both having a molecular weight of 22.5 kDa. Any heavy-chain type can associate with either light-chain type, but on any immunoglobulin molecule both light-chains are of the same type. Kappa and Lambda consist of a variable region and a constant region and can easily be differentiated by the antigenic properties of the constant region. The ratio of Kappa to Lambda is 70:30 , the vast majority of which is bound to heavy-chain in immunoglobulin. In normal individuals low levels of free light-chain arepresent in serum (kappa, 1.6-15.2 mg/L, Lambda, 0.4-4.2 mg/L), with the occurrence of multiple myeloma or other B-cell malignancies these levels can be greatly elevated and can be found at high levels in the urine (Bence-Jones proteins).
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