Partial amino acid sequence of an amyloid fibril protein from unusual cutaneous cystic lesions in myeloma-associated amyloidosis.
Although common cutaneous lesions in myeloma-associated systemic amyloidosis are petechiae, purpura, ecchymoses, plaques, waxy, translucent or purpuric papules or nodules, we encountered an unusual case of myeloma-associated amyloidosis with multiple cystic nodules. We isolated amyloid substance from the cutaneous cystic nodules of this patient and characterized it ultrastructurally, immunologically, and biochemically. Electron microscopy demonstrated that amyloid substances isolated by distilled water were principally straight and non-branching fibrils with a diameter of 8 to 10 nm, which was morphologically similar to amyloid fibrils. SDS-PAGE showed that these fibrils consisted of the 20 kDa and 29 kDa peptides, which reacted with the antibody to kappa light chain of immunoglobulin by immunoblot study. Partial amino acid sequence of N-terminal residues of this 20 kDa peptide showed a homology to kappa immunoglobulin light chain of variable subgroup I. These results suggest that amyloid fibrils in this unusual case with cutaneous cystic nodules may be derived from kappa I light chain of immunoglobulin.
Akiyama
T
T
Department of Dermatology, Ogaki Municipal Hospital, Minaminokawa-cho 4-86, Ogaki, 503-8502, Japan.
Seishima
M
M
Nojiri
M
M
Satoh
M
M
Ichiki
Y
Y
Kitajima
Y
Y
D000368:Aged; D000682:Amyloid / Q000737:chemistry* / Q000648:ultrastructure; D000686:Amyloidosis / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D003560:Cysts / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D008854:Microscopy, Electron; D009101:Multiple Myeloma / Q000150:complications*; D020539:Sequence Analysis, Protein; D012871:Skin Diseases / Q000150:complications / Q000378:metabolism* / Q000473:pathology
D000682:Amyloid