Polymeric Forms of Free Light Chains in Serum from Normal Individuals and from Patients with Renal Diseases

Abstract

The polymeric forms of free light chains from the immunoglobulins have been estimated in serum from 10 healthy individuals and from 10 anephric patients. Light chains were also estimated in serum and urine from 29 patients with various degrees of renal insufficiency. The measurements were carried out by a radioimmunoassay. The mean concentrations of light chains in normal serum were found to be 4.9 mg/l for dimeric forms of kappa chains, 5.6 mg/l for monomeric forms of kappa chains, 5.1 mg/l for dimeric forms of lambda chains, and 2.7 mg/l for monomeric forms of lambda chains. The concentration of light chains in anephric man was increased to 5 times the normal level. The concentration of the different forms was 26.7 mg/l for dimeric forms of kappa chains, 29.6 mg/l for monomeric forms of kappa chains, 32.6 mg/l for dimeric forms of lambda chains, and 5.8 mg/l for monomeric forms of lambda chains. A minor amount of tetrameric forms of kappa chains was found. Gel filtration showed that a majority of the kappa chains in normal and anephric serum existed as monomers and non-covalently linked dimers, whereas the lambda chains mainly existed as stable, covalently linked dimers. In renal disease the serum concentration of light chains was found closely correlated to creatinine clearance. The 24-h urinary excretion of light chains was generally increased when the GFR was diminished regardless of the type of renal disease.

Aggregation of Full-length Immunoglobulin Light Chains from Systemic Light Chain Amyloidosis (AL) Patients Is Remodeled by Epigallocatechin-3-gallate

“…When elevated LC levels in serum overwhelm renal absorption, LC is also found in the urine. Fulllength LC can be isolated from the urine of these patients (3)(4)(5).…”

Practical Considerations for the Measurement of Free Light Chains in Serum

“…If monoclonal FLCs undergo polymerization in serum, the M-protein may not be visible as a discrete band on electrophoresis but is present as a smear of different FLC polymeric forms (10 ). It has been reported from gel filtration analysis that in sera from patients with NSM and multiple myeloma (MM), FLCs may exist in multimeric forms in addition to the usual KFLC monomers and LFLC dimers present in serum (9,11 ).…”

Quantitation of serum free light chains does not compensate for serum immunofixation only when screening for monoclonal gammopathies

“…Therefore, some of the Bence Jones proteins detected in these patients might not be detectable by IFE because the ''true'' SFLC concentration was lower than that measured in the SFLC assay. In some patients with very high SFLC concentrations, it is more likely that the antiserum did not bind the respective light chain or that polymerisation of FLC (26) resulted in a negative IFE. However, monitoring SFLC in patients with intact immunoglobulins and increased SFLC might be important because renal involvement is detected in a high percentage of patients with multiple myeloma (27), which may be caused by the light chain component of the disease.…”