Fibrinolytic Activity in Human Saliva

Summary. 1. Human parotid saliva and mixed saliva from the mouth have been investigated in a search for a fibrinolytic system similar to the systems found in human blood, milk, lacrymal fluid, urine and seminal fluid. 2. Small and variable amounts of a plasminogen activator and large amounts of a proactivator of plasminogen were found. Plasminogen was absent. A slight trace of inhibitory activity against trypsin was recorded in only one sample. All other normal samples showed no inhibitory activity. 3. The fibrinolytic system in saliva thus differs from the system in blood and is similar to those in other secretions. 4. The activity was larger in unstimulated parotid saliva than in the stimulated parotid saliva from the same person.