Identification and characterization of different amyloid fibril proteins in tissue sections.

Antisera specific for 4 different classes of amyloid fibril proteins, amyloid protein AA and the immunoglobulin light-chain amyloid proteins AlambdaI, AlambdaIV, and AlambdaV, were used to identify these proteins directly in tissue sections from 25 patients with amyloidosis. The specificity of these reactions was established by blocking experiments with purified amyloid fibril proteins and Bence Jones proteins of known variable subgroups. Protein AA was detected in 17 patients, including all 13 with secondary amyloidosis, 2 with primary amyloidosis and 2 with Waldenström's macroglobulinemia. Immunoglobulin light-chain proteins AlambdaI, AlambdaIV, and AlambdaV were in 3, 1, and 2 patients, respectively, all of whom had primary or myeloma/macroglobulinemia-associated amyloidosis. Antiserum specific for the amyloid-related serum protein SAA reacted with the same tissues as anti-AA and had the same pattern of staining in tissue sections.