Octadecadienoic acids in the skin surface lipids of acne patients and normal subjects.

Measurements were made of the proportions of octadeca-5,8-dienoic acid and octadeca-9,12-dienoic acid in the scalp surface lipids of 6 normal subjects, 5 subjects with slight acne, and 9 subjects with severe acne. The group averages for the delta5,8 isomer were: 0.74, 0.85, and 0.61% and for the delta9,12 isomer were 0.56, 0.27, and 0.19%, respectively. The differences in the levels of the delta9,12 isomer between the normal subjects and the groups with slight and with severe acne were statistically significant (p less than 0.02 and 0.001), respectively) but there was no significant difference in the content of the delta5,8 compound. The ratio of the delta5,8/delta9,12 isomers showed no correlation with the rate of sebum production in 12 subjects.