Friday, June 1, 2012
A new category of rhinitis based on localized atopy
This month, Rondón et al. (J Allergy Clin Immunol 2012;129:1460-1467) present an important classificatory revision centered on their identification of a new rhinitis phenotype: local allergic rhinitis (LAR). Building on their previous research, the authors characterize LAR as local specific IgE (sIgE), TH2 local tissue response, and positive nasal allergen provocation test (NAPT) results in the absence of clinical indicators of systemic atopy, such as positive skin tests and serum specific-IgE. Patients with LAR are known to respond positively to nasal corticosteroids. In addition, they note that conjunctivitis and/or asthma can be comorbid with LAR.
Rondón et al. effectively argue that the current allergic versus non-allergic rhinitis (AR and NAR, respectively) distinction is not sufficient in light of the findings of localized atopy. They suggest that patients diagnosed with idiopathic rhinitis or non-allergic rhinitis with eosinophilia may in fact have LAR, which would decisively impact clinical management as patients with true idiopathic or non-allergic (vasomotor) rhinitis would not respond to therapy like LAR patients would.
The authors propose a revised rhinitis classification (Table 1, pp#) that splits allergic rhinitis into systemic and local atopy subcategories. They estimate prevalence from European data to be between 47-62% of patients reporting seasonal or perennial allergy symptoms. Their and other early results have shown that house dust mite, grass, and olive pollen are common triggers, though they note that comprehensive findings are needed to refine NAPT specificity.
Rondón et al. review the published pathophysiology evidence as well as the reported clinical presentation. They clearly identify the gaps that future research should fill, such as clinical management overlap between AR and LAR, the need for more practical NAPT testing procedures, the relationship between LAR and atopic march, and mechanisms of localized allergic responses. The authors comment that patients with LAR receiving subcutaneous immunotherapy have increased tolerance upon repeat NAPT and also develop positive skin tests and detectable serum specific-IgE.