ABSTRACT
Platelet-activating factor (PAF) is a phospholipid implicated in various pathophysiological conditions. Southern analysis using the cloned DNA indicates that the PAF receptor gene is present as a single copy in the human genome. The deduced protein sequence predicts seven hydrophobic regions for the PAF receptor. Lymphocytes expressing receptors for PAF (PAF-Rs) in their resting state already exhibited high-affinity PAF receptors after being activated for 1 day, with a maximum by days 4-6. The interactions of lipopolysaccharide with host cells can result in PAF synthesis, both in vitro as well as in vivo, during gram-negative infections. The role of PAF herein seems to be modest, as indicated by the lack of detectable PAF-R in human heart as well as the failure of PAF-R antagonists to influence the contractile function in heart muscle isolated from endotoxin-treated guinea pigs. Adhesion molecules, PAF are components of an adhesion, activation cascade. The facilitated interaction of target cells with membrane-bound chemotactic factors such as PAF induce high-affinity integrin-receptor binding.
