Abrogation of resistance to the reinduction of experimental allergic encephalomyelitis by pertussigen

Experimental allergic encephalomyelitis is an autoimmune disease initiated by an injection of myelin basic protein in complete Freund's adjuvant. Lewis rats which have recovered from the initial episode of hindquarter paralysis are resistant for at least 6 months to disease reinduction by basic protein-complete Freund's adjuvant, although specific antigen-reactive cells are detectable in convalescent rats. Resistance cannot be attributed to the activity of the adjuvant alone. In contrast, clinical disease could be reinduced by a secondary challenge with spinal cord homogenate and pertussigen (“lymphocytosis promoting factor” of Bordetella pertussis). Disease could also be reinduced by a simultaneous secondary challenge with basic protein-complete Freund's adjuvant along with pertussigen. Vascular permeability increases in the spinal cord paralleled disease induction or reinduction. No definite conclusions can be drawn concerning the mechanism by which pertussigen promotes disease reinduction in convalescent rats.