Current concepts of the formation and composition of amyloid

Immunochemical and chemical studies of purified amyloid fibril protein from a wide variety of human tissues reveals that amyloid fibrils may derive from immunoglobulin proteins most frequently in the "primary" disease and can be classified as of kappa- or lambda-type. In addition a protein of unknown origin is the source of amyloid fibrils in another group of cases usually of "secondary" type. The creation of fibrils with all the characteristics of amyloid fibrils has been accomplished by proteolysis of some Bence Jones proteins. This indicates that amyloid fibrils may be formed by proteolytic digestion of circulating light polypeptide chains of immunoglobulin proteins.