WASHINGTON, Jan. 4 (Xinhua) -- An international team identified how chemical compounds in creams and cosmetics cause rashes in the skin, suggesting a new way to treat the allergic condition.
The study published this week in the journal Science Immunology showed that an abundant molecule on the immune cells in the skin's outer layer exposes those chemicals to T cells that orchestrate the immune system's response to foreign chemicals.
Why some chemicals trigger dermatitis was a mystery, since small chemicals have to bind to a larger protein in order to become visible to T cells, but few chemicals do this by undergoing a chemical reaction inside our body.
Researchers at Columbia University, the Brigham and Women's Hospital, Cardiff University and Monash University found that several common chemicals known to trigger allergic contact dermatitis were able to bind to molecules called CD1a on the surface of skin immune cells and then activate T cells.
The chemicals include Balsam of Peru and farnesol, which are found in many personal care products, such as skin creams, toothpaste, and fragrances.
CD1a molecules bind the skin's own naturally occurring lipids in its tunnel-like interior. Those lipids protrude from the tunnel, creating a physical barrier that prevents CD1a from interacting with T cells, according to the study.
Farnesol, however, was shown to hide inside the tunnel of CD1a, displacing the resident natural lipids, making the CD1a surface visible to the T cells and resulting in an immune reaction.
The discovery offers a new idea for treatment as the allergic condition might be stopped by applying competing lipids to the skin to displace those triggering the immune reaction.
