SUBSTANCE-P ENHANCES ANTIGEN-EVOKED MEDIATOR RELEASE FROM HUMAN NASAL-MUCOSA

Exogenous substance P (10-80 nmol/ml) induced a dose-dependent increas e in nasal symptoms in asymptomatic allergies with rhinitis (n = 15) a nd controls (n = 8), but did not release any mediators. However, compa ring the antigen-evoked release of mediators into nasal secretions wit h that of a substance P-pretreated antigen challenge, we found a signi ficant enhancement of kinins, TAME esterase activity (p < 0.05-0.01), and histamine (p < 0.001, NS) 10-20 min after antigen challenge. These results suggest 1) that substance P-induced increase in nasal congest ion is mediated through direct neurokinin receptor activation independ ently of mast cell activation, and 2) that during the allergic reactio n there is a substance P-mast cell interaction that enhances the media tor response to nasal allergen challenge.