Analysis of the globose basal cell compartment in rat olfactory epithelium using GBC-1, a new monoclonal antibody against globose basal cells.

The olfactory epithelium (OE) supports ongoing neurogenesis throughout life and regenerates after experimental injury. Although evidence indicates that proliferative cells within the population of globose (light) basal cells (GBCs) give rise to new neurons, little is known about the biology of GBCs. Because GBCs have been identifiable only by an absence of staining with reagents that mark other cell types in the epithelium, we undertook to isolate antibodies that specifically react against GBCs and to characterize the GBC compartment in normal and regenerating OE. Monoclonal antibodies were produced using mice immunized with regenerating rat OE, and a monoclonal antibody designated GBC-1, which reacts against GBCs of the rat OE, was isolated. In immunohistochemical analyses, antibody GBC-1 was found to label GBCs in both normal and regenerating OE as we are currently able to define them: basal cells that incorporate the mitotic tracer bromodeoxyuridine and fail to express cytokeratins or neural cell adhesion molecule. During epithelial reconstitution after direct experimental injury with methyl bromide, expression of the GBC-1 antigen overlaps to a limited extent with expression of cell-specific markers for horizontal basal cells, Bowman's gland and sustentacular cells, and neurons. These data suggest that GBC-1 may mark multipotent cells residing in the GBC compartment, which are prominent during regeneration. However, a limited number of cells in the regenerating OE with other phenotypic characteristics of GBCs lack expression of the GBC-1 antigen. GBC-1 has revealed novel aspects of GBC biology and will be useful for studying the process of olfactory neurogenesis.