Intracutaneous injection of lysophosphatidylcholine induces skin inflammation and accumulation of leukocytes

Various cell stimuli act through activation of phospholipase Al, which hydr olyses fatty acids from membrane phospholipids, resulting in the formation of fatty acids and lysophospholipids. One of the lysophospholipid classes, lysophosphatidylcholine, is a chemoattractant for monocytes and T-lymphocyt es and induces the expression of adhesion molecules on cultured endothelial cells. The purpose of the present study was to determine whether lysophosp hatidylcholine possesses proinflammatory properties in vivo. This was asses sed clinically and histologically by intracutaneous injection of 200-800 nm ol lysophosphatidylcholine in healthy volunteers. Lysophosphatidylcholine e licited a dose- and time-dependent local erythema and oedema, The erythema disappeared within 4 h, while the induration lasted for up to 48 h, HE-stai ned biopsies taken after 24 h showed a leukocytoclastic vasculitis in 2 of the 6 subjects. Microscopic examination of immunohistochemically stained bi opsies taken 24 h after the injection showed a significant increase in the number of T-lymphocytes, monocytes and neutrophils, whereas the number of L angerhans' cells was unchanged after lysophosphatidylcholine injection. In addition, the number of intercellular cell adhesion molecule-1 and -3-posit ive cells was increased approximately 3-fold after injection of lysophospha tidylcholine. In conclusion, the phospholipase A(2) hydrolysis product lyso phosphatidylcholine can induce erythema, oedema, a mixed cellular infiltrat e and the expression of adhesion molecules.