Fibrinolytic proteases in QPD platelets.

Platelet lysates (lys; 3 μL) and releasates (rel; 3 μL) from patients with QPD (Q) and control subjects (C) were spotted onto fibrin substrate gels. (A) There was abnormal fibrinolytic activity in QPD platelet lysates and releasates that was blocked by the serine protease inhibitor AEBSF. The secretagogue ionophore A23187 (iono) released more of this activity from QPD platelets than ADP. (B) The fibrinolytic enzymes released by QPD platelets were not inhibited in 1:2 mixtures with normal platelet lysates or releasates (tested ratios of patient ionophore releasate–control samples are shown). Protein rings, without evidence of fibrinolysis, were seen in the tests of control lysates.