A comparative approach to secondary amyloidosis : Minireview

Abstract

In various species including phylogenetically lower animals, the pathological protein amyloid has been found. The characteristics of amyloid depend upon the β pleated structure of its fibrils. Various groups of amyloid can be distinguished based on the chemical properties of the fibrils which reveal a different major protein in each group: secondary amyloid, amyloid of immunoglobulin origin, APUD-amyloid, senile cardiac amyloid, and amyloid-like substances. In secondary amyloid, the major protein is protein AA which is related to the serum protein SAA. There is a relationship between induced secondary amyloid and the immune system, especially impairment of T cells and dysfunction of macrophages. The formation of protein AA containing amyloid will depend upon prolonged elevation of SAA levels and the extrusion of lysosomal enzymes from RE cells. The physiological relationship between SAA and the immune system, which it depresses, is unclear.