ABSTRACT
Amyloid is a pathological extracellular deposit composed predominantly of amyloid fibrils with characteristic morphology and pathognomonic tinctorial properties, specifically the capacity to bind Congo Red dye and then display red-green dichroism when viewed in strong cross polarised light. The deposits are rich in proteoglycans and always contain the non-fibrillar normal plasma glycoprotein, serum amyloid P component (SAP), which binds specifically to all amyloid fibrils. Amyloidosis is disease caused by amyloid deposits in the tissues. The deposits may be local or systemic in distribution and acquired or hereditary in aetiology. In amyloidosis the link between physical presence of amyloid deposits and disease is irrefutably strong. SAP is a highly conserved constitutive normal trace plasma protein with specific avid calcium dependent binding to all amyloid fibrils that causes its remarkable selective concentration and persistence in amyloid deposits of all types.
