Platelet-activating factor increases pulmonary microvascular permeability and induces pulmonary edema. A preliminary report.

Platelet-activating factor, a naturally occurring lipid that is released from leukocytes and alveolar macrophages, increased the flow of protein-rich lymph from the lungs and induced pulmonary edema in dogs when given in picomolar doses. The pulmonary edema was due to increased microvascular permeability, probably secondary to endothelial cell injury. These observations suggest that platelet-activating factor may be a mediator of high-permeability pulmonary edema in the "respiratory distress syndrome" complicating acute lung injury.