Urokinase-type plasminogen activator in human eccrine sweat.

Abstract

The presence of urokinase-type plasminogen activator (uPA) in human eccrine sweat has not been reported previously. Clean sweat was obtained from the upper trunk and arms of subjects which had been painted with white petrolatum to minimize epidermal contamination. Sweat was concentrated x 50 by ultrafiltration, and its PA activity determined by the two-step assay method (conversion of plasminogen to plasmin with the subsequent assay of plasmin activity using the substrate S-2251). PA activity was detectable in nine of 17 subjects by this method, which probably represents an underestimate of the true activity because of possible loss of the enzyme during concentration. Scraped (crude) sweat samples contained less PA activity. Sephacryl S-200 gel chromatography of the PA-positive pooled sweat showed a major peak of PA activity at M(r) 55,000. Gelatin-polyacrylamide enzymography revealed a major PA band at M(r) 55,000 and a minor band at 33,000. Sweat PA activity was 94% inhibited by epidermal PA inhibitor and anti-uPA IgG, but not by anti-tPA IgG. We conclude that the PA activity in sweat is derived from the sweat gland and is most likely of the urokinase type. The physiological significance of sweat uPA remains to be determined.