Total and allergen-specific immunoglobulin E in the serum and nasal mucosa of a nonallergic population

Background There has been a growing interest in measuring allergen‐specific immunoglobulin E (sIgE) directly from the nasal mucosal epithelium of individuals with sinonasal disease. However, there is currently no normative data with which to estimate sensitivity, specificity, and the appropriate positive cutoff level for new testing methods. Methods Twenty individuals with no history of sinonasal disease or food allergies underwent serum IgE testing and nasal mucosal brush biopsy (MBB) testing for total and sIgE to 7 common airborne allergens and 1 food allergen. The correlation between sIgE in serum and nasal samples was determined at both the 0.10‐kU/L and 0.35‐kU/L positive cutoff levels. Results sIgE at the 0.35‐kU/L cutoff level was detected for at least 1 allergen in 7 of 20 (35%) participants in both the serum and nose. At the 0.10‐kU/L cutoff level, 8 of 20 (40%) and 19 of 20 (95%) participants had sIgE to at least 1 allergen in the serum and nose, respectively. At the 0.35‐kU/L cutoff level, total serum IgE levels were significantly higher when at least 1 allergen was detected in the nose (p = 0.01). There was a strong association between sIgE in the serum and nasal mucosa (p < 0.0001) at both cutoff levels. Conclusion The significant association between serum and nasal samples for both total and sIgE suggests that nasal IgE and serum IgE are not independent of one another. Understanding levels of IgE in the nonallergic population will help answer the questions surrounding sensitization as new diagnostic tests for locally‐present IgE become available.