Correlation between Locally Produced Specific IgA and Eosinophil Cationic Protein in Nasal Lavage Fluids of Allergic Rhinitis Patients during Allergen Provocation Tests

Abstract

"Background: Eosinophils are the major effector cells in nasal allergic inflammation. However, the mechanism of eosinophil activation mediated by a series of inflammatory mediators presenting in early and late responses of allergic rhinitis (AR) is not fully understood.

Objective: The aim of this study was to evaluate the role of locally produced allergen specific antibodies in the nasal lavage fluid during the recruitment of inflammatory cells in AR.

Methods: Thirteen patients diagnosed with AR induced by sensitivity to Dermatophagoides pteronyssinus (Dp) according to positive responses to nasal provocation tests were enrolled in this study (positive group). Ten asymptomatic, sensitized subjects were enrolled as the control group. Of the positive responders, early (N = 7) and dual (N = 6) responders were categorized according to the presence of increased eosinophil counts 3 to 24 h after provocation. Nasal provocation tests were preformed with Dp-soaked paper disks, and nasal lavage fluids were collected before provocation and at 10, 30, and 60 min and 3, 6, and 24 h after the provocation test. The changes in symptoms were assessed with scores and acoustic rhinometry. Inflammatory cells, including eosinophils, were counted in the nasal lavage fluid. Eosinophil cationic protein (ECP), considered an active marker of inflammation, was measured by the CAP system. Specific IgE, IgG, and IgA antibodies to Dp were measured by ELISA.

Results: Eosinophil counts were significantly increased in the positive group compared with the control group at baseline. After nasal provocation tests, eosinophil counts continuously increased with a peak at 1 h, and the increased numbers persisted until 24 h in the positive group. Eosinophil counts at baseline and at 1 to 24 h after nasal provocation were significantly higher in dual responders than in early responders. Specific IgA levels were increased after provocation in both the early and late responses of the positive group, and statistical significance was noted at 10 min and 3 h. There were no significant differences in specific IgE and IgG levels during nasal provocation between the two groups. Significant correlations were observed between specific IgA and ECP levels at baseline and 10 min, and between 6 h and 24 h after nasal provocation (r = 0.58, p = 0.004; r = 0.81, p < 0.0001; r = 0.46, p < 0.023; and r = 0.61, p = 0.02).

Conclusion: Eosinophils act as major effector cells in both the early and late responses after allergen exposure in perennial allergic rhinitis. Locally produced allergen-specific IgA, but not specific IgE or IgG, in nasal mucosa may be involved in eosinophil activation in both the early and late responses.

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