Diagnostic performance of measuring free light chains in fat tissue of patients with AL amyloidosis.

摘要

The diagnostic performance was studied of measuring immunoglobulin free light chains in abdominal subcutaneous fat tissue for detection and characterization of AL amyloidosis. Fat tissue specimens of 107 patients with AL amyloidosis (23 kappa and 84 lambda) and 95 controls were studied. The amount of amyloid was graded semi-quantitatively in Congo red-stained specimens (0-4+). Amyloid was extracted from tissue in guanidine and free light chain concentrations were measured using nephelo-metry. Mean kappa and lambda concentrations in controls were 4.65 and 2.77 ng/mg fat tissue, respectively. Mean kappa/lambda ratio of controls was 1.69. With 0.49-5.86 as reference range for k/l ratio, 18 AL-K and 59 AL-L patients were identified (sensitivity 78 and 70%, respectively). Ninety-two controls had values in the reference range (specificity 97%). We conclude that measuring free light chains in fat tissue can indicate the presence of AL amyloidosis and can be used for characterizing amyloid as AL-kappa or AL-lambda.