Isolation and Characterization of Amyloid Enhancing Factor (AEF)

Abstract

Injection into mice of extracts of amyloid laden or of normal organs at the same time as a single potent inflammatory stimulus induces the extremely rapid deposition of systemic AA amyloid. This activity has been designated amyloid enhancing factor (AEF) and we report here a preliminary characterization of the material which confirms and extends previous work. AEF activity was extractable from normal murine organs as well as from amyloid laden tissues but in very much smaller amounts, and it was also present in normal or amyloidotic tissues of man, dog, and hamster. AEF extracts are very potent in vivo, as little as 0.002 A₂₈₀ units being effective. AEF activity was not inhibited by proteinase inhibitors, by nuclease or periodate treatment, by lipid extraction, or by low pH. It was, however, inactivated by proteolytic digestion or by alkaline pH treatment. Gel filtration indicated that the activity resided in a species of apparent molecular weight around 400,000. These findings suggest that AEF depends on a protein component possibly associated with non-protein material. Interestingly preparations of isolated human or murine AA fibrils had the same effect in vivo as AEF.