ABSTRACT
Immunoglobulin light chains are precursors of Primary amyloidosis (AL) amyloid fibrils. Free light chains can be quantified with a recently described immunoassay and appear to be useful in AL amyloidosis. The chapter aim is to study the value of serum free light chains for the diagnosis of systemic AL amyloidosis and for monitoring effects of therapy. Twenty-two patients with AL-kappa and 53 with AL-lambda amyloidosis were studied at diagnosis. Controls were 40 healthy blood donors, 9 patients with arthritis, 10 patients with AA amyloidosis, and 10 patients with ATTR amyloidosis. Free kappa and lambda light chains in stored serum samples were quantified with a nephelometric immunoassay with specific antibodies raised against hidden epitopes. The 99% confidence limits of controls were calculated for kappa, lambda, and the ratio of both light chains. Serum free kappa and lambda light chains, and especially the ratio of both, are valuable tools to diagnose AL amyloidosis and to monitor the clonal effect of therapy.
