Various cell stimuli occur via activation of phospholipase A₂, which hydrolyses polyunsaturated fatty acids from the sn‐2 position of membrane phospholipids, resulting in the formation of polyunsaturated fatty acids and lysophospholipids. The level of lysophospholipids is determined by the balance between phospholipase A₂ activity and the rate of catabolism of the lysophospholipids. One of the lysophospholipid classes, lysophosphatidylcholine, has been shown to stimulate certain leucocyte activities which are of importance for the induction and maintenance of inflammation. In addition, it has been demonstrated that phospholipase A₂ activity is increased in psoriatic skin.

In the present study, we analysed the levels of lysophosphatidylcholine, by thin layer chromatography, in lesional psoriatic skin, uninvolved psoriatic skin and normal skin. The lysophosphatidylcholine content, expressed as μmol lysophosphatidylcholine/μmol phosphatidylcholine, was 1.55, 0.21 and 0.12% in lesional psoriatic skin, uninvolved psoriatic skin and normal skin, respectively. The level of lysophosphatidylcholine was significantly elevated in lesional compared with uninvolved psoriatic skin (P= 0.004) and normal skin (P= 0.002). The increased lysophosphatidylcholine levels in psoriatic skin indicate that the phospholipase A₂ activation is not accompanied by a corresponding increase in the activity of enzymes catabolizing lysoPC.

If present in biologically active concentrations, lysophosphatidylcholine may contribute to the induction and maintenance of the inflammatory and immunological processes occurring in lesional psoriatic skin.