FURTHER STRUCTURAL AND ANTIGENIC STUDIES OF LIGHT-CHAIN AMYLOID PROTEINS

The major subunit protein of amyloid fibrils isolated from a patient with systemic amyloidosis and studied by N-terminal amino acid sequence analysis was almost identical to the sequence of a V.male.iIV Bence-Jones protein and a previously described A.lambda.IV amyloid protein. The 2 A.male.iIV amyloid proteins showed strong antigenic cross-reaction, appearing as antigenic identity in double immunodiffusion tests using anti-A.lambda.IV antiserum raised against one or the other of the 2 proteins. Another new A.lambda.V amyloid fibril protein showed strong amino acid sequence homology and antigenic identity in double immunodiffusions with the prototype of the A.lambda.V subgroup (the AR protein). Twenty primary or myeloma-associated amyloid proteins were characterized using antisera against the AA protein and several Ig L-chain-derived amyloid proteins.