Mammalian brain antigens defined by monoclonal antibodies

Seventy-two hybridoma lines that produce monoclonal antibodies to molecules of a rat synaptosomal plasma membrane fraction (SPM) were generated. The topographical distribution of the antigens in the cerebellum and other areas of the brain was studied by light microscopy immunocytochemistry. Some of the antibodies recognize exclusively neuronal antigens while others bind to specific glial molecules. Some of the antigens have a distribution limited to certain classes of neurons. There are antigens localized in both the cell bodies and processes while others are present only in the latter. Immunoblots of SPM proteins indicate that some antibodies react specifically with one or few of these proteins while other antibodies react with many. The latter antibodies also generally react with many brain cell types. Particularly interesting is the monoclonal antibody 8-6A2 which binds to many SPM proteins but only recognizes large neurons with long axons. A further characterization of the antigens was done by enzyme-linked immunosorbent assays and immunoblots of known purified proteins. The results indicate that antibody 8-2H5 binds specifically to clathrin, 8-7A5 to actin, 8-1E7 to the glial fibrillary acidic protein and both 8-3A5 and 7-2C12 to collagen. In contrast, the antibodies 4-4C3, 2-4H3, 4-4G7 and 6-6A8 bind to antigenic determinants present in many purified proteins.