Eicosanoids in skin of patients with atopic dermatitis: prostaglandin E2 and leukotriene B4 are present in biologically active concentrations.

The biochemical events leading to atopic dermatitis (AD) are unknown. Certain eicosanoids derived from arachidonic acid are potent mediators of skin inflammation and modulators of certain T-lymphocyte activities. The purpose of the present study was to determine whether eicosanoids are present in biologically active concentrations in the skin of adult patients with AD. The levels of the cyclooxygenase product, prostaglandin E2 (PGE2) and the lipoxygenase products, leukotriene B4 (LTB4), 12- and 15-hydroxyeicosatetraenoic acid were determined in biopsy specimens obtained by keratome from lesional, perilesional, and clinically unaffected skin of patients with AD. Methods for identification of eicosanoids included reversed-phase high-performance liquid chromatography combined with radioimmunoassays. Eicosanoid levels were at the same level in normal skin and in uninvolved skin of AD. Compared with uninvolved skin, both lesional and perilesional skin contained markedly elevated concentrations of PGE2 and LTB4: PGE2, 97.2 +/- 15.6 ng/gm of lesional skin and 128.3 +/- 27.2 ng/gm of perilesional skin; LTB4, 5.2 +/- 1.6 ng/gm of lesional skin and 3.2 +/- 0.6 ng/gm of perilesional skin. Compared with uninvolved skin, the levels of 12- and 15-hydroxyeicosatetraenoic acid were elevated sevenfold and elevenfold, respectively, in lesional skin, but did not reach biologically active concentrations. The results demonstrate that the inflammatory mediators PGE2 and LTB4 are present in lesional skin of atopic subjects in biologically active concentrations. Because these mediators are able to induce cutaneous inflammation and to modulate cellular immunity, they may be involved in the biochemical processes leading to AD.