Langerhans' cells in the skin have recently been shown to bind IgE molecules via the high-affinity IgE receptor (Fc epsilon RI). Using two highly specific antibodies against the antibody-binding alpha-chain of this receptor, 29C6 and 6F7, we demonstrate by immunohistochemistry and immunoelectron microscopy that Langerhans' cells of diseased nasal mucosa can express the Fc epsilon RI. Tissue sections from hyperplastic nasal conchae and nasal polyps of atopic and nonatopic patients have shown no basic differences in epithelial Fc epsilon RI-bearing cells. Only a few cells expressed the low-affinity IgE receptor (Fc epsilon RII) (Tü1 antibody) in some sections. These findings suggest that Langerhans' cells play an important role in the induction of transepithelial IgE-mediated allergy and in the mediation of inflammation of the nasal mucosa via their Fc epsilon RI.