The role of amyloid enhancing factor in the development of amyloid A amyloidosis /

Secondary, or AA, amyloidosis is a systemic disease characterized by the extracellular tissue deposition of insoluble, fibrillar amyloid A protein. Aberrant metabolism of serum amyloid A protein by reticuloendothelial cells in the presence of amyloid enhancing factor (AEF) is thought to result in the accumulation of fibrils within the tissue. Treatment of mice with AEF, in conjunction with an inflammatory stimulus, induces amyloid deposition within 48-72 hours. In vivo examination of the effect of AEF on spleen macrophage activation-associated phenotype and functions reveal that AEF has no apparent effect on the ability of spleen and liver macrophages to phagocytose or kill Listeria monocytogenes. It did appear to block enhanced respiratory burst function as well as result in a decrease in the number of cells expressing the MHC Class II surface antigen. Polyacrylamide gel electrophoretic purification of AEF from crude amyloidotic tissue extracts attributed AEF activity to a region apparently consisting of 3 protein species with molecular weights ranging from 63.2 KDa to 47.9 KDa. Ex vivo studies of macrophage function with protein eluted from this "AEF-active" region did not indicate an inhibition of respiratory burst suggesting that the action of AEF may be dependent on the presence of additional, possibly inflammation-associated, component(s)