A chemical found in the cannabis (hashish) plant can help the body's immune system alleviate a common skin disease called allergic contact dermatitis, according to a group of researchers from Israel, Germany, Italy, Switzerland and the US. The group was led by Dr. Andreas Zimmer of the University of Bonn and included cannabis expert Prof. Raphael Mechoulam of the Hebrew University of Jerusalem's School of Pharmacy. An article describing their research was published recently in the journal Science. They used the "endocannabinoid system" to alleviate the skin disease. There was a clear protective role for the endocannabinoid system in contact allergy in the skin, suggesting that development of cannabis-like compounds based on elements produced from the plant could enhance treatment for humans. Allergic contact dermatitis is caused by reaction to something that comes in direct contact with the skin. Many kinds of allergens can cause allergic contact dermatitis. Most people are not sensitive to them, but in those who are, any exposure will produce a rash, which may become very severe. Allergic contact dermatitis affects about 5 percent of men and 11% of women in industrialized countries and is one of the leading causes of occupational diseases. In his earlier work, Mechoulam's research group in Jerusalem isolated two naturally occurring cannabinoid (cannabis-like) components - one from the brain, named anandamide (from the word ananda, meaning "supreme joy" in Sanskrit), and another from the intestines named 2-AG. These two cannabinoids, plus their receptors and various enzymes that are involved in the cannabinoidsâ€š syntheses and degradations, comprise the endocannabinoid system. These materials have similar effects to those of the active components in hashish and marijuana, produced from the cannabis plant. Research throughout the world has since shown that the endocannabinoid system is involved in many physiological processes, including the protective reaction of the mammalian body to a long list of neurological diseases, such as multiple sclerosis, Alzheimer's and Parkinson's. In the Science article, the researchers explained how the endocannabinoid system serves as a major regulator of skin contact hypersensitivity in a mouse model. In this model, they showed, for example, that mice lacking cannabinoid receptors display exacerbated inflammatory skin responses to an allergen. Because the data indicate that enhanced activation of the endocannabinoid system may dampen the skin contact hypersensitivity response, the researchers administered cannabinoids such as tetrahydrocannabinol (THC), a constituent derived from the cannabis plant, to the lab animals. They found that the THC significantly decreased the allergic reaction in comparison to untreated mice.