Immunological studies of brain-specific antigens

Central nervous system antigens have been investigated, using immunofluorescence, to demonstrate the presence of antisera raised against regional homogenates of neonatal and adult rat brain. Heterologous antisera raised in rabbits against regions of rat brain contained several antibodies demonstrated by immunofluorescence. Brain-specific activity directed against neuronal and glial elements was difficult to characterise. Regional and age-dependent specificity of the antisera was not demonstrated. Homologous antisera could not be raised against neonatal rat brain regions, but low titre antibodies to neurones were detected in rats over 21 days old. These animals did not develop experimental allergic encephalomyelitis (EAE). In other rats which developed EAE following a different immunisation schedule similar antibodies were seen. It is concluded that heterologous antisera raised against unpurified antigens have too wide a spectrum of antibody specificities for use as anatomic markers. Homologous antisera are difficult to obtain in sufficiently high titre. There is production of antibodies towards neurones in one form of EAE.