Rat olfactory cells and a central nervous system neuronal subpopulation share a cell surface antigen

Using the monoclonal antibody (Mab) 6B7, a cell surface component found in adult rat central nervous system membrane preparations and on the surfaces of a subpopulation of neurons in cultures of embryonic rat forebrain has been identified. This Mab was derived from mice immunized with a rat forebrain synaptic plasma membrane preparation. High levels of Mab 6B7 binding are observed with membrane preparations from rat forebrain and olfactory bulb but no detectable binding is observed with membranes from the non-neural adult rat tissues heart, kidney, liver, lung and testes. Binding to dorsal root ganglia preparations was 5-fold lower than to forebrain. In immunofluorescence analyses, Mab 6B7 binds to the surface of a significant proportion of neurons in cultures of embryonic day 14 rat forebrain. However, it is absent from GFAP-positive astrocytes, oligodendrocytes, Schwann cells and fibroblastic cells in rat neural cultures. Due to the high levels of binding in olfactory tissue, the distribution of the 6B7 antigen in the olfactory epithelium was characterized in greater detail. In cryostat sections, 6B7 appears to react with a cell population of the basal layer of the adult rat epithelium, but is absent from the cell bodies of the more mature neuronal population which lies higher in the epithelium. This result suggests that within the olfactory epithelium Mab 6B7 may be useful as a marker for the proliferative basal cells which are the neuronal precursors in the epithelium. In summary, the 6B7 antigen may be useful in identifying and analyzing cell subpopulations in both the central nervous system and olfactory epithelium.