Suppression of acute experimental allergic encephalomyelitis by intraperitoneal administration of synaptosomal antigens

The effect of a synaptosomal fraction isolated from bovine brain was examined on acute experimental allergic encephalomyelitis (EAE) in Wistar rats. Intraperitoneal administration of the animals with low doses of saline-soluble synaptosomal antigens 10 and 3 days previous to the active induction of the disease was an effective way of suppressing EAE. This treatment diminished the incidence and severity of EAE, reverted the appearance of central nervous system histological and biochemical alterations, and produced changes in the autoimmune humoral response against the encephalitogenic myelin basic protein. The phenomenon observed by treatment with synaptosomal fraction is similar to the previously described suppression mediated by myelin antigens. Taking into account that affinity-purified antibodies and T lymphocytes specific for myelin basic protein can also recognize several neuronal proteins, among them the specific synaptosomal protein synapsin I, can be suggested that antigen-driven bystander suppression could be a mechanism by which synaptosomal proteins suppress the response against myelin antigens. J. Neurosci. Res. 53:187-194, 1998. (C) 1998 Wiley-Liss, Inc.