An improved quantitative method for the study of fibrinolysis in the skin as exemplified in patients with leukocytoclastic vasculitis and erysipelas

Abstract

The activity of plasminogen activator has been measured in tissue sections with the aid of a modified Todd technique. Frozen skin biopsies were sectioned and the tissue covered with fibrin-plasminogen film. After incubation at 37 degrees C fibrinolysis was studied for a period of 30 min and was graded into six exponentially increasing steps. During this period, grades were linear with the llogarithm of time of incubation. The rate of fibrinolysis is a measure of the activity of the plasminogen activator and is expressed by the slope of the linear regression of grades versus the ogarithm of time; the value of the slope is proportional to the common logarithm of the activity of the plasminogen activator present in the section. Using urokinase as a specific plasminogen activator, the same linear expression was shown with time, indicating the validity of our grading and experimental system. Eleven healthy subjects served as controls to 6 patients with leukocytoclastic vasculitis and 4 patients with erysipelas and 4 with necrotizing fascilitis. The controls showed values similar to the non-involved skin in the patients. The activity was higher in the arm than in the thigh sites. The activity in the thighs was lower in women than in men. A decrease in the plasminogen activator activity was found in the three disorders.