Abnormalities in epidermal lipid metabolism in patients with atopic dermatitis.

Atopic dermatitis is an inflammatory skin disease characterized by dryness and itch of the skin. In this study, we measured the phospholipid content and the fatty acid pattern of lesional and lesion-free epidermal keratome biopsies on 15 patients. For comparison, epidermal biopsies were obtained from healthy individuals undergoing plastic surgery. The phospholipid content of atopic epidermis was nearly twice as high as in healthy epidermis. Monounsaturated fatty acids in the phosphoglycerides were significantly increased (p less than 0.001) and n-6 fatty acids were significantly decreased (p less than 0.001) in lesional atopic epidermis compared to lesion-free epidermis. The content of esterified arachidonic acid in phosphatidylcholine from lesional epidermis was only 49% of that found in healthy epidermis (p less than 0.001). The content of free arachidonic acid was 47% higher (p less than 0.05), whereas the content of free long-chain saturated fatty acids was decreased by 29% (p less than 0.01), in lesional compared to lesion-free atopic epidermis. The disease severity, calculated as an arbitrary index, correlated inversely with the n-6 fatty acid content of lesion-free atopic epidermis (r = -0.89, p less than 0.001). Our findings suggest that atopic epidermis is characterized by an increased activity of phospholipase A2 and an incomplete transformation of phospholipids into other lipid classes.