Neuronal nitric oxide synthase immunoreactivity in the nasal mucosa of patients with idiopathic and allergic rhinitis

The localization of neuronal nitric oxide synthase (nNOS) in the mucosa of the inferior and middle turbinates of 30 patients with and without allergic rhinitis was examined by immunohistochemical methods. Staining of paraffin sections from allergic and nonallergic patients revealed nNOS immunoreactivity (nNOS-IR) in the muscular layer of vessels, in the basal portion of submucosal glands and in the periost and the osteocytes of the turbinate bones. In contrast to earlier investigations, nNOS-IR was also seen in the nasal respiratory epithelium of allergic and nonallergic patients. The immunostaining of sections of submucosal glands from allergic patients was stronger than that of sections from patients with idiopathic rhinitis or patients with no nasal obstruction. The present result - nNOS-IR around glands is elevated in patients with allergic rhinitis - could indicate that this enzyme is involved in the pathogenesis and symptomatology of allergic rhinitis.