Characterization of an amyloid fibril protein from localized amyloidosis of the skin as lambda immunoglobulin light chains of variable subgroup I (A lambda I).

Amyloid fibrils obtained from a case (Hud) of localized, tumorous amyloidosis of the skin were investigated by immunological and biochemical methods including amino acid sequence studies. Evidence was obtained that a lambda immunoglobulin light chain protein, A lambda I, and differently sized N terminal fragments (mol. wt 14,000 and 10,000) of the same protein comprised a major component of the fibrils. The chemical nature of this protein suggested that this case of cutaneous amyloidosis belonged to the idiopathic form of amyloidosis, probably as a special type of systemic, idiopathic amyloid disease.