Identification of the neuritogen for experimental allergic neuritis

Abstract

EXPERIMENTAL ALLERGIC NEURITIS (EAN) is a model of human acute inflammatory polyneuropathy, Guillain–Barré syndrome. It can be produced in several species of laboratory animal by immunisation with homologous or heterologous peripheral nerve emulsified in Freund's complete adjuvant^1,2. After about two weeks the animals may develop signs varying from ataxia to paralysis and death. EAN has been produced using crude acid extracts of peripheral nerve^3,4, but investigations into the neuritogenic properties of the component proteins of peripheral nerve myelin have yielded inconclusive results^5–10. In experimental allergic encephalomyelitis (EAE), the central nervous system (CNS) counterpart of EAN, the encephalitogenic antigen has been shown to be a CNS myelin basic protein of molecular weight 18,000 (ref. 11). The three major proteins of peripheral nerve myelin, which together account for about 75% of the myelin protein, are usually referred to as P₀, P₁ and P₂ (ref. 12). P₀ is a glycoprotein of molecular weight 30,000 and P₁ and P₂ are both basic proteins with molecular weights of 18,000 and 12,000–14,000, respectively^12–13. We describe here a reliable method for producing severe EAN in inbred Lewis rats with bovine intradural root material, and show that intact P₂, the major basic protein of peripheral nerve myelin, is the responsible neuritogen.