Prevention of experimental allergic encephalitis in Lewis rats by rat and bovine spinal cord proteins.

Abstract

EXPERIMENTAL allergic encephalitis (EAE) is an inflammatory autoimmunedisease of the central nervous system (CNS) that is mediated by T lymphocytes sensitised to the organ-specific basic protein (BP) of CNS myelin2. Lesions of delayed hypersensitivity develop in the brain and spinal cord when sensitised lymphocytes traverse the walls of CNS blood vessels and react with the target antigen in myelin3. EAE can be prevented by injecting BP in Freund's incomplete adjuvant (FIA) before challenge, suppressed by injecting BP soon after challenge and treated by injections of BP after clinical symptoms appear4. Prevention, suppression and treatment are immunologically specific for BP and can be dissociated from the production of humoral antibody against BP5. The demonstration that pretreatment of guinea pigs with bovine spinal cord protein (BSCP)6,7 prevented the development of EAE8,9 is thus of considerable importance because BSCP is chemically and antigenically distinct from bovine BP and is not encephalitogenic. As pretreatment with SCP induced a state of nonspecific unresponsiveness to bovine BP in the guinea pig, we investigated whether SCP had anti-encephalitogenic activity in the Lewis rat, a highly inbred rat strain used extensively for the study of EAE. We report here that Lewis rats pre-treated with rat SCP (ref. 10) were protected against EAE, as they did not develop the disease when they were subsequently immunised with rat myelin BP in complete Freund's adjuvant (CFA).