Permeability-increasing ability of PAF-acether in rat skin

Platelet-activating factor (PAF-acether), a phospholipid compound with effects on several cells, e.g., platelets and polymorphonuclear leukocytes (PMNs), was examined for its effect on microvascular permeability in rat skin. It was found to increase microvascular permeability, measured as exudation of [125I]human serum albumin, in amounts exceeding 1 pmol, and was more than 1000 times as potent as histamine. The effect was independent of cell infiltration, as no accumulation of PMNs, measured as the amount of myeloperoxidase in the skin, occurred and as the response was unaltered in animals rendered neutropenic due to treatment with an antiserum against PMNs.