Studies on autoimmune encephalomyelitis in the guinea pig IV. Relative independence of acute and chronic diseases

Abstract

Young guinea pigs immunized with homologous or isologous brain tissue often presented two successive and different episodes of disease: first, acute classical experimental allergic encephalomyelitis (EAE) and second, after recovery a chronic EAE episode. There was no relation between incidence and severity of the acute episode and incidence and severity of the chronic episode in the same animals. Induction of the first acute disease was not modified with boiled brain tissue or isolated homologous basic protein of brain myelin (BP) as immunogens, while the chronic disease did not appear. EAE-inducing capacity of brain tissue was enhanced in its acute form and reduced in its chronic form after treatment with phenol. Isolated brain myelin was able to induce both diseases (boiled myelin induced only the acute disease). In central nervous system tissue two autoantigens exist, both in myelin: BP, resistant to heating and phenol treatment and responsible for the induction of acute EAE, and a second autoantigen referred to as M2, heat- and phenol-sensitive, which could share with BP the responsibility of chronic EAE induction.