Tryptase in nasal lavage fluid after local allergen challenge: Relationship to histamine levels and TAME‐esterase activity

The activation of mast cells is generally considered to be an important trigger mechanism in the immediate allergic response. This study focused on the determination of three markers of mast cell activation after an allergen challenge. Nasal allergen challenges were performed in 25 subjects with seasonal allergic rhinitis using three allergen doses increasing in 10‐fold steps in a standardised nasal lavage model for the subsequent recovery of the markers of mast cell activation. The levels of histamine and tryptase in the nasal lavage fluid were determined using radioimmunoassays, while the TAME‐esterase activity was determined using a radiochemical technique. The nasal symptoms obtained on challenge were assessed using a scoring technique. The allergen challenge resulted in significant increases in the levels of all three markers, tryptase, histamine and TAME‐esterase. In the individual measurements after the challenges there was a highly significant correlation between the TAME‐esterase levels and the tryptase levels (r = 0.71; P < 0.001), while the generation of histamine and tryptase was not significantly correlated. When comparing the cumulative generation of the three markers, significant correlations were found between all three. Allergen challenges in six non‐allergic controls using the same technique did not result in any increase in tryptase levels. The findings suggest that the determination of tryptase in nasal lavage fluid may be a valuable indicator of mast cell activation in the upper airways.