Effects of allergen immunotherapy on the nasal mucosa in patients with allergic rhinitis

Despite the varied immunological changes occurring after allergen immunothe rapy, the precise mechanism, or the mechanisms responsible for clinical eff ectiveness of allergen immunotherapy have not been clearly determined. Post ulated immunomodulatory mechanisms include a decrease in cellular responsiv eness, a production of blocking antibodies, a reduction in the number of ma st cells. and activation of T-cell suppressor mechanisms. Nineteen allergic rhinitis patients (study group) with house dust mite sensitivity and 10 no nallergic control subjects were studied, in the study group, the nasal muco sal biopsies were obtained prior to immunotherapy and were repeated after I year, and specimens were evaluated by light and electron microscopy. After the third month of immunotherapy, nasal symptom scores were reduced signif icantly and disappeared in the sixth month (p <0.01). No significant change s were observed in the levels of immunoglobulins, IgG subclasses and comple ment levels (p <0.05), except lgG4/IgG1 ratio (p <0.05). A comparison of hi stopathological findings of nasal mucosa in each case revealed an improveme nt in epithelial loss, inflammation, thickening of basal membrane and fibro sis (p <0.05). A significant correlation was observed between epithelial lo ss and mast cell accumulation with symptom score (p <0.001). These results suggest that the improvement of nasal epithelial cells and reduction of mas t cell accumulation in nasal mucosa may be one of the mechanisms that could explain the improvement of nasal allergy symptoms following immunotherapy.