The Association of Nasal and Blood Eosinophils with Serum IgE Level in Allergic Rhinitis and Asthma: A Case-Control Study.

Background and aims: Allergic rhinitis and asthma are two common respiratory diseases with allergic etiology in the world's population. Eosinophils and serum IgE levels have been known as inflammatory allergy markers for many years. This study aimed to evaluate the correlation of nasal and blood eosinophils with serum IgE levels in allergic rhinitis and asthma patients.

Methods: This prospective study was done on patients (n = 78) diagnosed with asthma (n = 20), allergic rhinitis (n = 49), and chronic rhinosinusitis with nasal polyposis (CRSwNP) (n = 9) at our hospital in Ahvaz City, Iran. The age of participants in our study ranged from 3 to 73 years, and all of them were subjected to a complete blood count (CBC) test, nasal smear, and determination of serum IgE levels after their consent.

Results: There was no correlation between serum IgE level and nasal eosinophil count (p = 0.728) or between serum IgE level and blood eosinophil count (p = 0.657); however, a positive correlation was detected between blood and nasal eosinophil levels (p = 0.003).

Conclusion: There is no significant relationship between serum IgE level and eosinophil count in the blood and nasal secretions. Serum IgE level and blood or nasal eosinophil count are both useful biomarkers for monitoring allergic rhinitis and asthma individually, but no diagnostic conclusion can be drawn from their correlation.