Phosphoinositide breakdown and superoxide anion release in formyl-peptide-stimulated human alveolar macrophages....

Human alveolar macrophages (AMs) from allergic asthmatics (AAs) showed continuous Li+-sensitive production of IP1, indicating that the cells were continuously activated. Furthermore, whereas the accumulation of IP1, IP2 and IP3 rapidly increased by as much as 125-175% in chemotactic-factor-stimulated AMs from healthy subjects, stimulation of cells from AAs increased these inositol phosphates only slightly. This moderate production could be due to a permanent state of activation leading to a depleted pool of polyphosphoinositides, corroborating the greater capacity of these cells to generate superoxide anion after stimulation by a chemoattractant. The activation state could be due to the action of priming agents, which are known to be released into the inflammatory sites.