The effect of etretinate on the cyclo-oxygenase and lipoxygenase products of arachidonic acid metabolism in psoriatic skin.

Eight psoriatic patients were treated with etretinate (50 mg daily) for 6 weeks. Skin chamber exudates from involved and uninvolved skin were assayed for arachidonic acid, 12-HETE, PGE2 and for neutrophil chemokinetic activity co-chromatographing with leukotriene B4, before and at weekly intervals during therapy. Pre-treatment concentrations of arachidonic acid, 12-HETE and leukotriene B4-like chemokinetic activity but not of PGE2 were elevated in involved skin when compared to uninvolved skin.

The analysis of arachidonic acid metabolites in normal, uninvolved and lesional psoriatic skin.

Collection of exudate from suction bullae is a commonly used method for sampling human skin for mediator analysis. It is satisfactory on skin of normal structure but is unreliable on lesional psoriatic skin in which there are major structural changes and excessive scaling. Collection of exudates from abraded sites was found to be a suitable alternative method for psoriatic skin.