DEMONSTRATION OF MAST-CELL CHEMOTACTIC ACTIVITY IN NASAL LAVAGE FLUID- CHARACTERIZATION OF ONE CHEMOTAXIN AS C-KIT LIGAND, STEM-CELL FACTOR

Mast cells are known to accumulate in tissue during allergic inflammat ion. However. the chemotaxins responsible are undefined. Using a modif ied Boyden chamber and the human mast-cell line HMC-1, we first identi fied mast-cell chemotactic activity in nasal lavage fluid collected be fore the pollen season after allergen provocation of allergic patients (n=29) (mean migratory response compared to medium control was 121%, range 85-198%). Mast-cell chemotactic activity was also detected in la vage fluid collected after allergen provocation at the end of a Swedis h birch-pollen season from three different treatment groups: topical s teroid treatment with budesonide the topical antihistamine, levocabast ine; and placebo. There was no significant difference in mast-cell che motactic activity between nasal lavage fluid collected from the placeb o group (mean=102%), the budesonide-treated group (mean=114%), or the levocabastine group (mean=125%). Stem cell factor (SCF), a known mast- cell chemotaxin, was present in the nasal lavage fluids from all three groups, and correlated with the mast-cell chemotactic activity (r=0.6 7, P<0.01). The mast-cell chemotactic activity was inhibited (range 5- 100%) in some, but not all, nasal lavage fluids by a polyclonal antibo dy directed against SCE This report describes the presence of mast-cel l chemotactic activity in nasal lavage fluid during an allergic reacti on. These findings show that SCF may play a pivotal role in the recrui tment of mast cells in allergic rhinitis.