Chymase is a potent chemoattractant for human monocytes and neutrophils.

Chymase is a major chymotrypsin-like serine protease expressed in the secretory granules of mast cells in many mammalian species. In this study, we revealed the chemotactic activity of chymase for human mononuclear cells and neutro- phils with a 48-well microchemotaxis chamber technique. Human chymase showed the potent chemotactic activity for monocytes and neutrophils dose-dependently in a concentration range from 0.1 to 10 µg/mL, corresponding to about 4-400 µM. The activity was as potent as that of N-formyl- methionyl-leucyl-phenylalanine. Chymase also stimulated cell migration of lymphocytes and puri- fied T cells, but checkerboard analysis revealed that the effect was chemokinetic rather than chemo- tactic. Inhibition of chymase activities with chy- mase inhibitors, such as antileukoprotease and Bowman-Birk soybean trypsin inhibitor, signifi- cantly inhibited the chemotactic activity of chy- mase, suggesting that the proteolytic activity of chymase participates in the chemotactic activity. Our results suggest that mast cell chymase acts as a chemoattractant, and may play a role in the accumu- lation of inflammatory cells in development of the chronic inflammatory responses of allergic and nonallergic diseases. J. Leukoc. Biol. 67: 585- 589; 2000.