Skin creams and cosmetics can sometimes produce rashes instead of a beautiful complexion, but why has been a mystery until now.
A new study suggests that some chemicals in these products remove natural fats in skin cells, which might be why they trigger allergic reactions.
When the immune system spots something foreign, its T-cells spring into action, the researchers explained.
“However, many small compounds that trigger allergic contact dermatitis lack the chemical groups needed for this [allergic] reaction to occur,” said study author Annemieke de Jong, an assistant professor of dermatology at Columbia University Vagelos College of Physicians and Surgeons.
“These small chemicals should be invisible to T-cells, but [sometimes] they’re not,” she said in a Columbia news release.
De Jong and her colleagues believed that CD1a, a molecule on the skin’s outer layer, might be the culprit that makes certain chemicals visible to T-cells.
In experiments with human skin cells, the researchers found that several common chemicals known to cause allergic reactions were able to bind to CD1a molecules and activate T-cells.
The chemicals included Balsam of Peru and farnesol, which are found in many products such as skin creams, toothpaste and fragrances. The researchers identified more than a dozen small chemicals that activate T-cells through CD1a.