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Abnormal free light chain production has also been reported to be prognostic of a worse outcome in multiple myeloma [36] [37] [38] and chronic lymphocytic leukaemia. [39] An abnormal light-chain ratio has been defined as a kappa to lambda chain ratio of less than 0.26 or more than 1.65. [32]
Once set, light chain class remains fixed for the life of the B lymphocyte. In a healthy individual, the total kappa-to-lambda ratio is roughly 2:1 in serum (measuring intact whole antibodies) or 1:1.5 if measuring free light chains, with a highly divergent ratio indicative of neoplasm. The free light chain ratio ranges from 0.26 to 1.65. [1 ...
[70] [79] These biomarkers are >60% clonal plasma cells, a serum involved / uninvolved free light chain ratio ≥ 100 (the concentration of the involved free light chain must be ≥ 100 mg/L) and more than one focal lesion ≥ 5 mm by MRI. [70] [79] Together, these biomarkers and the CRAB criteria are known as myeloma-defining events (MDEs).
Serum protein electrophoresis showing a paraprotein (spike/peak in the gamma zone) in a patient with multiple myeloma.. A myeloma protein is an abnormal antibody (immunoglobulin) or (more often) a fragment thereof, such as an immunoglobulin light chain, that is produced in excess by an abnormal monoclonal proliferation of plasma cells, typically in multiple myeloma or Monoclonal gammopathy of ...
In practice, this is inferred by the detection of only one of the mutually exclusive antibody light chains, kappa or lambda, on the entire population of the abnormal B cells. Normal B lymphocytes consist of a stew of different antibody-producing cells, resulting in a mixture of both kappa- and lambda-expressing cells.
AL amyloidosis is caused by the deposition of abnormal antibody free light chains. The abnormal light chains are produced by monoclonal plasma cells, and, although AL amyloidosis can occur without diagnosis of another disorder, it is often associated with other plasma cell disorders, such as multiple myeloma and Waldenström's macroglobulinemia. [6]
Light chain MGUS is defined as a disorder in which a serum κ to λ free light chain ratio falls outside the normal range of 0.26–1.65 (mean =0.9) provided that it is not associated with: a) any of the CRAB criteria, b) a bone marrow plasma cell count of 10 or a higher percentage of nucleated cells, c) evidence of amyloid deposition (see ...
High-resolution electrophoresis and serum and urine immunofixation are recommended to help identify and characterize the monoclonal IgM paraprotein. The light chain of the monoclonal protein is usually the kappa light chain. At times, patients with Waldenström macroglobulinemia may exhibit more than one M protein. Plasma viscosity must be ...