Seasonal idiopathic rhinitis with local inflammatory response and specific IgE in absence of systemic response

Background: Patients with idiopathic rhinitis (IR) are considered to be nonallergic because they have a negative skin prick test (SPT) and allergen specific-IgE in serum. The concept of localized mucosal allergy in the absence of atopy has recently been proposed. The immunological mechanisms involved in seasonal IR have not been sufficiently studied. We examined nasal mucosa inflammation, the presence of nasal specific-IgE and the response to nasal allergen provocation test (NAPT) in patients with seasonal IR who presented symptoms only in spring. Methods: We evaluated 32 patients with seasonal IR and 35 with persistent allergic rhinitis to pollen (PAR-P) and compared these with healthy controls and persons with PAR to house dust mite during the pollen season, as well as by NAPT out-of-season with grass and Olea europea. We measured the nasal leukocyte-lymphocyte phenotype (CD45, CD33, CD16, CD3, CD4 and CD8), eosinophil-cationic-protein, and total and specific-IgE to grass and olive pollen in serum and nasal lavage and performed NAPT. Results: In the IR group, 62.5% had a positive NAPT (IR-PosNAPT), 20/32 to grass, with four of these having a positive NAPT to olive pollen as well. IR-PosNAPT patients showed a similar nasal leukocyte-lymphocyte profile to the PAR-P patients and different to controls. We detected nasal specific-IgE in 35% of IR-PosNAPT patients. Conclusions: These results support the hypothesis that a subgroup of patients with IR have seasonal symptoms with evidence of a nasal allergic immune reaction in the absence of a positive SPT or serum specific IgE.