Electron Microscopy of the Arthus Reaction, Using Ferritin as Antigen

Abstract

Arthus reactions produced in skin and muscle of rabbits and guinea pigs sensitized to ferritin were examined with the electron microscope. Aggregated ferritin molecules surrounded by an amorphous material of lesser electron density were widely distributed throughout the reactive site and were similar morphologically to in vitro ferritin-anti-body complexes. A circumferential distribution of ferritin-antibody complexes was seen in and on either side of the basement membrane of small blood vessels. This suggests that such localization may prelude the vascular damage which is a prominent histological feature of the reaction. The study provides visual evidence at a molecular level that antigen and antibody are present in the reactive site of the Arthus lesion.