The effect of some protease substrates and inhibitors on chemotaxis and protease activity of human polymorphonuclear leukocytes.

Both low- and high-molecular-weight inhibitors of serine proteases were found to inhibit chemotaxis by human polymorphonuclear leukocytes totally at widely varying concentrations. Synthetic low-molecular-weight substrates with trypsin-like or chymotrypsin-like specificity were also shown to be potent inhibitors of chemotaxis. Chemotactic inhibition was reversible except with a titrant for the active site of a serine protease. N-acetyl-L-tyrosine ethyl ester was found to be a suitable substrate for measuring protease activity of polymorphonuclear leukocyte. Concentrations of the various protease inhibitors that caused 100% chemotactic inhibition caused 80%-100% inhibition of protease activity of polymorphonuclear leukocytes.