Comedogenicity of Human Sebum

The components in human sebum that mediate the formation of comedones in the rabbit ear were evaluated by applying various sebum fractions as well as individual authentic components of sebum. Practically all the major constituents of sebum had some activity. The activities of the triglycerides and waxes were respectively moderate and weak. Among the saturated fatty acids activity began at C₁₀, reached a peak at C₁₂and C₁₄, lessened at C₁₆and C₁₈, and was absent at C₂₀. Monounsaturation increased comedogenicity but high unsaturation had the opposite effect. Irritancy and comedogenicity were shown to be unrelated properties. The lower fatty acids C₃and C₅were highly irritating and noncomedogenic while C₁₆and C₁₈were comedogenic and non-irritating. The sebum of various animals had borderline comedogenicity because of the absence of triglycerides and fatty acids.