Idiopathic and allergic rhinitis show a similar inflammatory response

HYPOTHESIS: Idiopathic and allergic rhinitics have similar mucosal mast cell and IgE+ cell distribution. INTRODUCTION: The pathophysiology of idiopathic rhinitis (IR) is unknown but patients differ from those with allergic rhinitis (AR) in that they do not express IgE. Our study is novel because we investigated: (1) three study groups chosen prospectively using strict selection criteria over a 4-year period; and (2) mast cell and IgE+ cell counts were on full-thickness, full-length inferior turbinate mucosa. METHODS: Patient groups: allergic (n = 17); idiopathic: (n = 16); and normal controls (n = 9). Immunohistochemistry: mast cell and IgE+ cell detection using anti-mast cell tryptase and anti-IgE antibodies with an avidin-biotin (peroxidase) complex on paraffin processed tissue. Morphometry: sections were divided into three strata comprising an epithelial layer and two submucosal layers. Statistics: Mann-Whitney non-parametric analysis. alpha = 0.05, beta = 0.2. RESULTS: The power of the study was 89%. Mast cells (P = 0.03) and IgE+ cells (P < 0.05) were significantly increased in the epithelium of idiopahtic and allergic rhinitis mucosa compared to the normal control. More IgE+ cells were counted in the AR and IR groups compared to the controls in all three strata. CONCLUSION: Mast cells and IgE+ cells are involved in the pahtophysiology of IR. We propose that IR may be a variant form of AR involving a localized IgE-mediated inflammatory response.