[Amyloidosis]

Recent studies have clearly indicated that amyloid is a generic term which includes a number of different substances, all of which have a beta-pleated sheet structure and a characteristic fibrillar appearance in the electron microscope. The most common types are made of immunoglobulin light chain (AL) fragments in the primary and myeloma-associated type, and of the AA protein in the secondary and some familial forms. It seems probable that other localized types are composed of prohormones or other tissue proteins. In systemic amyloidosis, the fibrils seem to be derived from a soluble circulating precursor; immunoglobulin light chains give rise to AL, and the SAA protein, which behaves as an acute phase reactant yields AA, presumably by proteolysis. It is not known whether the disease is due to overproduction or a defect in degradation. Though effective therapeutic agents are still lacking, colchicine has proved useful in preventing or ameliorating the amyloid in Familial Mediterranean Fever and in several experimental forms of the disease. It deserves careful study as a possible therapeutic agent on other types of amyloidosis.