Abstract: Objective To study the efficacy and mechanism of compound Tripterygium hypoglaucum Hutch (THH) on photoallergic contact dermatitis in mice. Methods The photoallergic animal model of BALB/c mice was established by using photosensitizer chlorpromazine and UVA irradiation. The therepeutic efficacy was determined by measuring the thickness and the weight of the swelling ear and the number of infiltrated mononuclear cells in the ear tissue. Immunohistochemical technique was used to detect the ICAM-1 expression on keratinocytes, fibroblasts and vascular endothelial cells. The serum level of INF-γ was measured by ELISA. The tested animals were divided into 3 groups:compound THH, THH alone and normal saline. Results The difference of the thickness of left ear before and after challenge, the differences of the thickness and the weight of ear tissue, the difference of the number of infiltrated mononuclear cells of left and right ear after challenge were significantly less in the compound THH group than those in the THH alone group (P<0.05) and normal saline group (P<0.01). The levels of ICAM-1 expression on skin lesion and INF-γ in serum were also markedly lower in the compound THH group than those in the normal saline group and THH alone group respectively (P<0.05). Conclusions The compound THH has marked suppressive action on photoallergic reaction and is more effective than THH alone. The mechanism may be that it can suppress the ICAM-1 expression in the skin and the INF-γ production in lymphocytes so as to reduce lymphocytic infiltration and relieve the allergic reaction.

Key words: Tripterygium hypoglaucun Hutch, Dermatitis, photoallergic, Intercellular adhesion molecule-1, Interferon type Ⅱ, Mice, inbred BALB/c