Local production of IgE in the respiratory mucosa and the concept of entopy: does allergy exist in nonallergic rhinitis?

Objective: To review research regarding locally produced IgE and its impact on patients with chronic rhinitis. Data Sources: PubMed search with the following keywords: entopy, local IgE, nonallergic rhinitis, idiopathic rhinitis, vasomotor rhinitis, and allergic rhinitis. Study Selection: Articles were selected based on their relevance to entopy and locally produced IgE and its clinical effect and relationship to idiopathic rhinitis (IR). Results: Local IgE has been found in a variety of tissues, including nasal and bronchial mucosa. IgE is produced in these local tissues and not simply the product of migration to the tissue from regional lymphoid tissue or blood. Local IgE has been identified in most of both atopic and nonatopic asthmatic patients and allergic rhinitis patients. Up to 40% of patients with IR and a positive nasal provocation test result have evidence of locally produced IgE, which has been coined entopy. Although patients with allergic rhinitis and IR show similar inflammatory patterns with increased activated mast cells, eosinophils, and T-cell subsets in some studies, other studies on IR patients are conflicting with regard to both inflammation and allergen-specific nasal provocation test results. Conclusion: The concept of local allergy in IR patients is both intriguing and controversial. Studies have reported conflicting results, and currently there is no single best test to evaluate for entopy. It is known that there are a large number of IR patients for whom current treatment regimens are suboptimal. Therefore, further research elucidating the mechanisms of IR and the concept of localized IgE are needed to optimally diagnose this condition and treat this group of patients. Ann Allergy Asthma Immunol. 2010;105:249-256.