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Why some creams and cosmetics lead to skin rashes, study explains

ANI | Updated: Jan 04, 2020 15:12 IST

Washington D.C. [USA], Jan 4 (ANI): Several different chemical compounds found in creams and cosmetics can cause allergic reactions on the skin, but how the reaction gets triggered has been a mystery. However, now a study has suggested possible reasons why some chemicals trigger dermatitis.
The study led by researchers at Columbia University Irving Medical Center, the Brigham and Women's Hospital, and Monash University explained the way some chemicals displace natural fat-like molecules (called lipids) in skin cells.
Published online in Science Immunology, it talks of the reason behind why some chemicals trigger.
Poison ivy is a commonly known trigger for allergic contact dermatitis, an itchy skin rash. But many ingredients found in nonprescription topical products can trigger a similar type of rash.
An allergic reaction begins when the immune system's T cells recognize a chemical as foreign. T cells do not directly recognize small chemicals, and research suggests that these compounds need to undergo a chemical reaction with larger proteins in order to make themselves visible to T cells.
"However, many small compounds in skincare products that trigger allergic contact dermatitis lack the chemical groups needed for this reaction to occur," says study co-leader Annemieke de Jong, PhD, assistant professor of dermatology at Columbia University Vagelos College of Physicians and Surgeons.
"These small chemicals should be invisible to T cells, but they're not," De Jong added.
The research team suspects a molecule - CD1a, which is abundant on Langerhans cells (immune cells in the skin's outer layer), might be responsible for making these chemicals visible to T cells.
In the current study, the researchers found that several common chemicals known to trigger allergic contact dermatitis were able to bind to CD1a molecules on the surface of Langerhans cells and activate T cells.
These chemicals included Balsam of Peru and farnesol, which are found in many personal care products, such as skin creams, toothpaste, and fragrances.
"Our work shows how these chemicals can activate T cells in tissue culture, but we have to be cautious about claiming that this is definitively how it works in allergic patients," De Jong said.
De Jong further stated: "The study does pave the way for follow up studies to confirm the mechanism in allergic patients and design inhibitors of the response."
The only solution that is currently found to stop allergic contact dermatitis is to identify and avoid contact with the offending chemical. If prone to rashes, topical ointments can help soothe the rashes, which usually clear up in less than a month.
In severe cases, physicians may prescribe oral corticosteroids, anti-inflammatory agents that suppress the immune system, increasing the risk of infections and other side effects. (ANI)

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