Inflammatory activity of a trypsin-like protease in the tuberculin reaction sites in guinea pig skin.

A trypsin-like protease(s) was found in the extracts from tuberculin reaction sites in the guinea pig skin. Extractable enzyme activities were chronologically paralleled with the gross appearance of the inflammation, and the maximum activity from 24-hour old inflamed sites was about 12 times stronger than that from control skin, suggesting a potential role in the pathogenesis of the delayed hypersensitivity reaction (DHR). The enzyme suitably hydrolyzed t-butyloxycarbonyl-phenylalanyl-seryl-arginine 4-methylcoumaryl-7-amide, and was partially purified by gel filtration. It showed an apparent molecular weight of 700,000 with optimal pH of 9.0-9.5. The activity was inhibited by various serine protease inhibitors but not by thiol or metal protease inhibitors. It was relatively heat-stable. These findings suggest that the protease is similar to a trypsin-like protease from DHR to bovine gamma-globulin. Intradermal injection of the enzyme into normal guinea pigs induced a mixed neutrophil-mononuclear infiltrate. The reaction was reduced in intensity with the diisopropylfluorophosphate-inhibited enzyme preparation. The enzyme did not induce any increased vascular permeability. These findings suggest that the protease may be present generally in the DHR sites and probably participates in the cellular response of DHR.