BIOCHEMICAL AND HISTOLOGICAL ANALYSIS OF 2 MULLER CELL ANTIBODIES IN DEVELOPING AND ADULT CAT AND RAT CENTRAL-NERVOUS-SYSTEM

We investigated the binding characteristics of two monoclonal antibodi es, 4F3 and 3F8, which in the retina specifically stain Muller cells, both with protein blots and immunohistochemically in sections of vario us regions of the central nervous system of neonatal and adult cats an d rats. Clear differences emerged between the two antibodies. In addit ion, some species-specific as well as developmental differences within the staining pattern of each individual antibody were evident. The ep itopes recognized by 4F3 lay mainly in the 57-63 kDa range. Histologic ally, 4F3 labelled mainly glia cells: oligodendrocytes and astrocytes in optic nerve, astrocytes in neocortex and cerebellum, Bergmann glia in the cerebellum and radial glia in neonatal animals. This was confir med by double-immunofluorescence with the astrocyte marker GFAP. By co ntrast, 3F8 epitopes lay mainly in the 47-49 kDa range. Histologically , 3F8 la belied oligodendrocytes in the optic nerve, but only neurons in cerebellum and neocortex as confirmed by double-labelling with neur onal markers. Neither 4F3 nor 3F8 recognized GFAP or vimentin. These r esults clearly indicate (1) that the two antibodies identify new epito pes/molecules, (2) that the antigens are not retina-specific, and (3) that Muller cells share epitopes with other glial cells as well as wit h neurons outside the retina.