IMPAIRED ANAPHYLACTIC RESPONSES WITH INTACT SENSITIVITY TO ENDOTOXIN IN MICE LACKING A PLATELET-ACTIVATING-FACTOR RECEPTOR

Platelet-activating factor (PAF) is a potent phospholipid mediator wit h diverse biological activities in addition to its well-known ability to stimulate platelet aggregation. Pharmacologic studies had suggested a role for PAF in pregnancy, neuronal cell migration, anaphylaxis, an d endotoxic shock. Here we show that disruption of the PAF receptor ge ne in mice caused a marked reduction in systemic anaphylactic symptoms . Unexpectedly, however, the PAF receptor-deficient mice developed nor mally, were fertile, and remained sensitive to bacterial endotoxin. Th ese mutant mice clearly show that PAF plays a dominant role in eliciti ng anaphylaxis, but that it is not essential for reproduction, brain d evelopment, or endotoxic shock.