Measurement of PLG activators and uPA activity in serum samples from normal, healthy donors and patients with confirmed leptospirosis. Paired serum samples from individuals with confirmed leptospirosis in the initial (MAT-negative) or convalescent (MAT-positive) phase or serum samples from healthy donors (Normal) were quantified for the presence of uPA (A) or tPA (B) by specific capture ELISA kits. The quantification was based on uPA and tPA standard curves. The symbols represent the individual dosage of each sample, and the horizontal bars represent the medium. In panel C are shown the measurements of uPA activity by specific activity test. Plotted in the graphic is the activity determinate of each serum sample. The horizontal bars represent the means of the serum samples for each group. Statistically significant values were calculated by comparing MAT-negative and MAT-positive samples with the control sera (normal): *, P < 0.006; **, P < 0.130; ***, P < 0.06.