Inflammatory characteristics of PAF-acether in the skin of experimental animals and man.

PAF-acether (AGEPC) is released from a range of inflammatory cell types and has properties consistent with those of a mediator of inflammation. Intradermal injection of PAF-acether in experimental animals causes immediate extravasation of plasma protein, accompanied by intravascular accumulation of platelets and neutrophils; this is followed by persistent extravascular accumulation of neutrophils and mononuclear cells. We have studied the inflammatory characteristics of intradermally injected PAF-acether in human skin. An early (weal and flare) response is succeeded, in 60% of subjects, by a late-onset area of erythema at the site of the resolved weal, reminiscent of the dual response to allergen in sensitized individuals. The time course and dose-response relationship of the early response was determined and a synergistic interaction between PAF-acether and prostaglandin E2 established. The weal response to PAF-acether was not inhibited by concurrent administration of chlorpheniramine. Histopathological examination of serial elliptical biopsies revealed accumulation of both neutrophils and mononuclear cells in response to intracutaneous PAF-acether. We would suggest that PAF-acether is likely to be a mediator of both acute and persistent inflammation.