Using Local sIgE Threshold to Refine the Diagnosis of Local Allergic Rhinitis

BACKGROUND: Local allergic rhinitis (LAR) is a chronic rhinitis (CR) phenotype with localized IgE production but no systemic atopy. Diagnosis relies on the nasal allergen challenge (NAC), but its correlation with the underlying immunological endotype is unclear, necessitating a more reliable biomarker. Therefore, this study was conducted to evaluate a local specific immunoglobulin E (sIgE) threshold for diagnosing house dust mite (HDM)-sensitized LAR and compare its immunological relevance to the conventional NAC-based method. METHODS: This prospective study enrolled 181 CR patients without systemic atopy and 146 healthy controls. All CR patients underwent NAC. Local sIgE levels of Dermatophagoides pteronyssinus and Dermatophagoides farinae were measured in nasal secretions. A diagnostic threshold was established using the 95th percentile from the healthy cohort. The NAC and sIgE-based stratifications were then compared by analyzing patients' nasal cytokine profiles. RESULTS: Classification based on NAC positivity did not reveal significant differences in local sIgE or a consistent type 2 inflammatory signature. In contrast, stratification using the established local sIgE threshold (≥ 0.14 kUA/L) identified a local sIgE-high group with significantly elevated levels of type 2 cytokines (IL-4, IL-5, CCL5, and CCL11) compared to the sIgE-low group (all p < 0.05). Furthermore, local sIgE levels positively correlated with these type 2 cytokines in the sIgE-high group. CONCLUSION: A local sIgE threshold reliably identifies an immunologically distinct LAR endotype, aligning diagnosis with its type 2 pathophysiology. This biomarker-driven approach offers a precise tool to refine diagnostic algorithms and improve patient selection for targeted therapies.