Heparin attenuates the release of histamine and tryptase induced by AMP nasal provocation

Abstract

Rationale Previous studies have shown that inhaled heparin attenuated the airway responses to allergen, exercise and AMP bronchial provocation, possibly through an inhibition of mast cell activation. The objective of the current study was to determine whether inhaled heparin affect the release of mast cell mediators, histamine and tryptase, induced by AMP nasal provocation. Methods Nine atopic and six non-atopic subjects received placebo and heparin (15,000 units USP/mL) 15 min before a AMP nasal provocation in a double blind crossover study design. The nasal lavage was collected from these subjects prior to or 3, 5, 15 or 30 minutes after the AMP nasal challenge, and concentrations of histamine and tryptase in the nasal lavage were measured. Results In atopic subjects, when received placebo, AMP nasal provocation induced a transient increase in the histamine and tryptase release with peak values achieved at 3–5 minutes after the challenge. In comparison, inhaled heparin significantly attenuated the release of histamine and tryptase induced by AMP challenge (p=0.02 and 0.012, respectively). In non-atopic subjects, AMP did not induce a significant increase in histamine and tryptase release in both placebo day and heparin treatment day. Conclusions These data suggest that AMP nasal provocation causes mast cell mediator release in a similar fashion as that induced by AMP bronchial provocation. In addition, the data support the hypothesis that inhaled heparin plays a protective role against AMP provocation by inhibition of mast cell activation.