Chronic relapsing experimental autoimmune encephalomyelitis. Ultrastructure of the central nervous system of animals treated with combinations of myelin components.

Guinea pigs with long-standing chronic experimental autoimmune (allergic) encephalomyelitis were treated with myelin basic protein (MBP) alone in incomplete Freund's adjuvant or MBP in combination with a lipid hapten, galactocerebroside in incomplete Freund's adjuvant and studied for up to 26 months post-treatment. Animals which received MBP/galactocerebroside consistently displayed a long-lasting, marked, clinical improvement within 3 months post-treatment. Of 14 animals treated with MBP/galactocerebroside four have been sampled for light and electron microscopy. The central nervous systems of these animals displayed widespread remyelination and profound oligodendroglial proliferation. Some oligodendroglia appeared to be of recent origin. This structural recovery had occurred against a background of advanced gliosis and fibrosis. Treatment with MBP alone was associated with an initial period of stabilization, but after several months, relapsing activity and disease progression returned. It is suggested that after prolonged autoimmune demyelination, oligodendrocytes can proliferate in the presence of advanced scarring, that central nervous system remyelination can be effected, and that these findings have relevance to multiple sclerosis.