Amyloidosis and the respiratory tract

Amyloidosis is a,generic term for a heterogeneous group of disorders associ ated with deposition of protein in an abnormal fibrillar form.(1) The diver se spectrum of amyloid related diseases is now recognised to include Alzhei mer's disease, type II diabetes, and the transmissible spong,iform encephal opathies. Amyloidosis can be hereditary or acquired, localised or systemic, and potentially lethal or merely an incidental finding. Amyloid deposits consist mainly of protein fibrils, the varying peptide sub units of which constitute the basis for its classification (table 1).(2) De spite much heterogeneity among their respective precursor proteins, all amy loid fibrils have a remarkably similar adopted ultrastructure and share man y physicochemical properties attributable to their acquired rich beta-sheet content.(3) Certain glycosaminoglycans (GAGs) are invariably associated wi th the fibrils and, in addition, all amyloid deposits contain the normal pl asma protein serum amyloid P component (SAP). The specific binding interact ion between SAP and all amyloid fibrils is the basis for our development of radiolabelled SAP as a diagnostic nuclear medicine tracer.(4) (5) There have been many recent advances in amyloidosis including elucidation o f the structure and properties of amyloid fibrils, the role of GAGs and SAP , and substantial improvements in clinical diagnosis and management. Althou gh a specific generic treatment for the disease is not yet available, compe lling evidence that amyloid deposits frequently regress when the supply of the respective fibril precursor protein is reduced has encouraged a much mo re positive approach to patient care.(5).