Interaction of leukocytes and endotoxin with the plasmin and kinin systems

Leukocytes can generate a substance that, when added to some partially purified human kininogen, is capable of forming kinins. The addition of endotoxin or polystyrene latex particles to the incubated leukocytes doubled the amount of kinin generated. Certain preparations of kininogen, however, failed to allow kinin formation by the leukocytes. No evidence could be found that an activator of prekallikrein or a kallikrein was present in the granulocyte preparations. However, the addition of highly purified plasminogen to inactive kininogen preparations restored their ability to generate kinins in the presence of leukocytes. All the kininogen preparations that allowed kinin formation when incubated with leukocytes contained plasminogen. These data suggest that a plasminogen activator is present on the leukocyte surface. This activator activates plasminogen to form plasmin which in turn acts on kininogen to release a kinin and thus provides a mechanism for the formation of kinins in inflammatory exudates and during endotoxemia.