Local and Systemic Eosinophilic Responses in Children With Allergic and Infectious Rhinitis

Background. Allergic and infectious rhinitis overlap clinically in children. Total serum IgE, peripheral blood eosinophils and nasal eosinophils reflect different aspects of systemic and mucosal inflammation. Objective. To compare these markers between children with allergic and infectious rhinitis and between seasonal and perennial allergic phenotypes. Methods. This retrospective study analysed records of 149 children aged 1–15 years: perennial allergic rhinitis (PAR, n=56), seasonal allergic rhinitis (SAR, n=30), infectious rhinitis (IR, n=39) and healthy controls (n=24). Diagnoses were clinical, without skin-prick testing or allergen-specific IgE measurement. Total serum IgE and nasal cytology results were available for all groups; blood eosinophil results were available for the three patient groups. The criteria used to classify IgE as elevated could not be verified retrospectively. Proportions were compared using chi-square or Fisher's exact tests. Results. Elevated total serum IgE was recorded in 69/86 (80.2%) children with allergic rhinitis versus 19/39 (48.7%) with IR (p<0.001), and in no controls. Nasal eosinophils were detected in 72/86 (83.7%) children with allergic rhinitis versus 13/39 (33.3%) with IR (p<0.001), and in no controls. Nasal eosinophil proportions above 10% occurred in 32/86 (37.2%) children with allergic rhinitis, but in none of the children with IR or healthy controls. In the IR group, proportions above 5% occurred in 3/39 (7.7%) children. Blood eosinophilia above 5% was more frequent in SAR than PAR (18/30, 60.0% versus 18/56, 32.1%; p=0.023). Nasal eosinophilia did not differ significantly between allergic phenotypes at either the >5% or >10% threshold; elevated IgE also showed no significant difference (p=0.42). Conclusion. Nasal eosinophilia was more frequent in clinically diagnosed allergic rhinitis. Blood eosinophilia was more frequent in seasonal than perennial disease. IgE findings require caution because classification criteria could not be verified. These exploratory comparisons describe differences between clinically defined groups and do not establish diagnostic accuracy.