The composition of the ceramides from human stratum corneum and from comedones

Human epidermal surface lipids were collected by an ethanol wash and the ceramides were quantified by thin-layer chromatography-photodensitometry. Six ceramide fractions were isolated and the structural components of each were analyzed in detail. The most unusual of the epidermal ceramides contained a sphingosine base with amide-linked 30- and 32-carbon omega-hydroxyacids and an ester-linked nonhydroxyacid, 41% of which was linoleic acid. The proportion of linoleic acid in the analogous ceramide from comedones was 6%. This supports the hypothesis that a localized insufficiency of linoleic acid in the follicular epithelium is an etiologic factor in comedogenesis.