Increase in anti-astrocyte antibodies in the serum of guinea pigs during active stages of experimental autoimmune encephalomyelitis

From previous studies on the induction and treatment of experimental autoimmune encephalomyelitis (EAE) in guinea pigs and mice, antibodies have been implicated during both demyelination and remyelination. In the present study, sera from guinea pigs with acute, chronic and myelin basic protein/galactocerebroside (MBP/GC)-treated chronic EAE were evaluated for the presence of anti-glial cell antibodies by immunocytochemical techniques. Antigen specificity was confirmed by enzyme-linked immunosorbent assay (ELISA) and Western blotting. The majority of sera from acute and chronic active EAE animals displayed intense labelling of astrocytes and only weak staining of oligodendrocytes when tested on sections of normal guinea pig brain tissue. In contrast, sera from animals with chronic EAE treated with MBP/GC gave strong labelling of oligodendrocytes and only minor staining of astrocytes. By immunoblotting, astrocyte staining was shown to be due to the presence of anti-glial fibrillary acidic protein (GFAP) antibodies. The intense oligodendrocyte staining observed in sections reacted with sera from MBP/GC-treated guinea pigs corresponded well with high titers of serum anti-GC and anti-MBP antibodies measured by an ELISA. It was concluded that the presence of antibodies against astrocytes was possibly related to astrocytic antigens within the disease-inducing emulsion, at least during the initial phases of EAE, and not to their release from the central nervous system of affected animals.