SUBSTANCE-P, CALCITONIN-GENE-RELATED PEPTIDE, AND VASOACTIVE-INTESTINAL-PEPTIDE INCREASE IN NASAL SECRETIONS AFTER ALLERGEN CHALLENGE IN ATOPIC PATIENTS

Background: There is suggestive evidence that neuropeptides participat e in allergic reactions. Substance P (SP) and calcitonin gene-related peptide (CGRP) are released by sensory nerves, whereas vasoactive inte stinal peptide (VIP) is released mainly by parasympathetic nerves. Bot h sets of nerves are thought to be stimulated by allergic inflammation . The aim of this study was to assess nasal secretions to determine wh ether SP CGRP, and VIP were increased after allergen challenge. Method s: Eight patients with allergic rhinitis were challenged nasally with 1 mg histamine or increasing doses of allergen. Nasal lavages were col lected into a cocktail of protease inhibitors in order to restrict neu ropeptide degradation. Radioimmunoassay for SP CGRP, and VIP were perf ormed on each sample. Results: All patients had immediate clinical rea ctions to both histamine and allergen challenges, and seven patients e xperienced a later allergic reaction. After histamine challenge, SP an d CGRP did not increase significantly above baseline in the nasal lava ges, whereas VIP did (p < 0.02). In contrast, SP, CGRP, and VIP all si gnificantly increased immediately after allergen challenge and returne d to baseline within 2 hours. At the clinical peak of the late allergi c reaction, SP, but not CGRP or VIP was increased slightly but signifi cantly (p < 0.01). Conclusions: Thus SP CGRP, and VIP are found in nas al secretions after allergen challenge, which confirms that neuropepti des are released in human beings during allergic reactions. The select ive stimulation of VIP secretion by histamine challenge suggests that histamine-induced cholinergic reflexes induce the release of VIP. Thes e data support the suggestion that neuropeptides may be partly respons ible for some of the nasal symptoms of allergy.