Systemic effects of allergen exposure on blood basophil IL-13 secretion and FcεRIβ

Background: Airway allergen challenge studies have shown the upregulation of cytokines in local airway tissues and distal effects on bone marrow precursors for eosinophils and basophils. Objective: We investigated whether local intranasal allergen challenge alters the phenotype of circulating basophils to a primed state. Methods: Ten subjects with allergic rhinitis were challenged with allergen by means of intranasal spray on 3 sequential days. Basophils were isolated from subjects before challenge and 3, 24, and 96 hours after the third allergen challenge. Basophils were compared before challenge and after the last allergen challenge for levels of Fcis an element ofRIbeta protein by means of Western blotting and for Fcis an element ofRIbeta mRNA expression by means of realtime PCR. Basophils were also compared with regard to spontaneous secretion of IL-4 and IL-13. Results: Basophil Fcis an element ofRIbeta protein levels increased in 5 of 6 subjects after allergen challenge relative to before challenge. Likewise, basophil Fcis an element ofRIbeta mRNA levels increased a median of 2-fold after the last challenge relative to before challenge (P = .007, n = 9). IL-13 protein was detected in supernatants of 7 of 9 subjects' basophil-enriched cultures after the last challenge compared with 3 of 9 basophil-enriched cultures before challenge (median, 6.2 vs 0 pg/mL; P = .058). IL-4 was not detected in any culture supernatant. Conclusion: Intranasal allergen challenge transiently activates circulating basophils by increasing expression of the Fcis an element ofRIbeta subunit and spontaneous IL-13 secretion. Because Fcis an element ofRIbeta is an amplifier of Fcis an element ofRI-mediated responses and IL-13 is proinflammatory, these findings support a primed basophil functional state and demonstrate a systemic effect of local allergen challenge that could contribute in exacerbating allergic reactions.