The suppressive effect of evening primrose oil on murine contact sensitivity

Background: Evening primrose oil (EPO) is a rich source of cis-linoleic acid and gammalinolenic acid (GLA) and has been used as a therapeutic agent in various skin diseases such as atopic dermatitis. Objective: The purpose of this study was to evaluate the suppressive effect of EPO on murine contact sensitivity. Methods: BALB/c mice were divided into 3 groups, positive control, experimental and negative control groups: the positive control group represents a group of mice which were sensitized and challenged with DNFB, the experimental group represents EPO-pretreated positive control group and the negative control group represents a group of mice which were challenged only. The changes of ear thickness were measured, and H and E staining and immunohistochemical staining for ICAM-1 expression of ear skin were performed to evaluate the histological changes of each group. Results: The pretreatment of mice with EPO resulted in suppression of contact sensitivity by more than 82%. On H and E staining, only a mild inflammatory reaction was observed in the dermis. Also ICAM-1 expression of keratinocytes, the intensity of the staining was significantly decreased in the experimental group compared with positive group. Conclusions: Our study indicates that EPO was able to suppress the induction of contact sensitivity.