A molecular basis of cell death in olfactory epithelium.

When the membrane receptor Fas binds its ligand, Fas ligand (FasL), an apoptotic cascade is initiated in the cell bearing the Fas receptor. The same can be said about the tumor necrosis factor receptor-1 (TNFR1) and its ligand, TNF-alpha. In this study we have shown that the mRNAs of both sets of ligands and receptors, Fas/FasL and TNF-alpha/TNFR1, were present in unperturbed olfactory epithelium. Fas and FasL were shown by immunohistochemistry and by Western blots of bulbectomized animals to be in the neurons and in some non-neuronal (microvillar) cells of unperturbed rat olfactory epithelium. Addition of either FasL or TNF-alpha to organotypic cultures of fetal rat olfactory epithelium resulted in a significant increase in the number of apoptotic bodies after 4-6 hours. These data raise the possibility that either or both ligand-receptor pairs participate in cell death in the olfactory epithelium. Copyright 1999 Wiley-Liss, Inc.