Human skin proteases: effect of separated proteases on vascular permeability and leukocyte emigration in skin

The effect of human skin proteases on vascular permeability and leukocyte emigration in rabbit skin was investigated. The alkaline protease of human skin capable of hydrolysing trypsin substrate effectively increased vascular permeability. This effect was not inhibited by antihistamine, but almost totally so by Trasylol. The reaction was protracted. Leukocyte emigration in skin, primarily of PMN-cells at 12 hrs, and later a migration of mononuclear cells, also resulted. Swelling of the dermal fibres was noted. The alkaline protease of human skin capable of hydrolysing chymotrypsin substrate also increased vascular permeability, but this phenomenon was effectively inhibited by antihistamine and the reaction was of brief duration. The leukocyte emigration caused by this enzyme was remarkable. The acid proteases of human skin resembling cathepsin B1 and D also caused brief increased vascular permeability, which was effectively inhibited by antihistamine. The cellular reactions to these acid proteases were mild. The role of protease inhibitors in skin in the enzyme reactions is discussed.