Immunoelectron microscopic findings in patients with allergic rhinitis

Abstract

In middle Europe the prevalence of allergic rhinitis is up to 15 % to 25 %. Allergic rhinitis is characterised by an inflammation of the nasal mucosa induced by different allergens. The patients suffer from symptoms like sneezing, rhinorrhea and nasal airway obstruction caused by morphological changes of the nasal mucosa. This symptomatology is considered to be a result of accumulation and activation of inflammatory cells. Further some neuropeptides like Calcitonin Gene Related Peptide (CGRP) and Substance P (SP) play an additional role in pathophysiology of allergic rhinitis. Tissue samples from 28 human turbinates of patients with perennial rhinitis were taken during nasal surgery and preserved in phosphate-buffered glutaraldehyde or paraformaldehyde. Ultrathin sections were cut. The samples were dehydrated and embedded in Araldit. After polymerization an immunocytochemical staining-technique using a gold-labeled antibody was carried out. Immunostained structures were photodocumented by using a transmission electron microscope. In the lamina propria mucosae an extensive edema and several inflammatory cells like lymphocytes, plasma cells, eosinophiles and macrophages was found. The capillaries showed an activated endothelium. Immunoreactive nerve fibers were found in the periglandular tissue around the acini, ducts and in the glandular connective tissue. Neuroglandular synapses with dense core vesicles and positive immunoreactions to CGRP and SP could be detected. Neuropeptidergic axons were often observed near to plasma cells. In the edematous nasal mucosa an infiltration with different inflammatory cells was found. Using electron microscopical techniques nerve structures near the submucosal glands could be demonstrated. Immunoreactions to the neuropeptides CGRP and SP were detected in the periglandular nerves and in neuroglandular synapses. These findings demonstrate the direct nerve control of glandular functions in allergic rhinitis. CGRP is generally known to have a vasodilatatory effect and to stimulate the secretion of nasal seromucous glands. In addition, SP as a short-acting vasodilatator may induce vascular permeability and glandular secretion. These immunoelectron microscopical findings further elucidate pathomorphological mechanisms in allergic rhinitis.