Researchers may have found the process behind allergic reactions to cosmetics and skin creams, according to a new study. Photo by Hans Braxmeier/Pixabay
Jan. 6 (UPI) -- Those who suffer from allergic reactions to certain cosmetics and skin creams may be one step closer to finding relief for their annoying symptoms, thanks to new research into what causes these problems in the first place.
An international team of dermatologists, rheumatologists and immunologists has identified CD1a, a molecule found in human skin cells, as the culprit in a complex process that triggers allergic contact dermatitis, or ACD, an increasingly common condition, particularly in the United States. They suggested that confirming CD1a's role in the development of ACD could provide future researchers with a pathway for developing new treatments for condition.
The researchers published their findings Friday in the journal Science Immunology.
"ACD is very common, and in many cases the mechanism by which certain chemicals cause an immune reaction in the skin is incompletely understood," study co-author Annemieke de Jong, assistant professor of dermatology at Columbia University Vagelos College of Physicians and Surgeons, told UPI. "We had been investigating the role of the CD1a protein in skin immunity for many years."
Poison ivy is perhaps the best-known trigger for ACD, but it can also be caused by many ingredients in soaps, cosmetics, fragrances, jewelry, toothpaste and plants -- although, until now, why this is the case has remained a mystery. The reaction often appears as a red, itchy rash that isn't contagious or life-threatening, but often very uncomfortable.
Currently, there is no treatment for ACD, other than avoiding contact with the chemical causing it, although topical ointments can help sooth the rashes. In some severe cases, prescription oral corticosteroids may be needed, and these medications can increase a person's risk for infections, among other side effects.
To begin the process of finding alternatives, de Jong and her colleagues decided to explore how the skin's immune cells respond to the introduction of the chemicals found in consumer products. The team suspected that CD1a, which is found in the skin's Langerhans -- or immune -- cells might be responsible for making these chemicals visible to T cells, the cells that trigger immune system response.
To test their hypothesis, they exposed human T cells in tissue culture to material from skin patch testing kits used in allergy clinics. In general, they found that the T cells responded to certain substances, including balsam of Peru, a tree oil widely used in cosmetics and toothpaste. Specifically, two chemicals found in balsam -- benzyl benzoate and benzyl cinnamate -- were directly responsible for stimulating the T cell response.
In all, they identified a dozen chemicals, including farnesol, that appeared to elicit a similar response. The authors believe these chemicals cause ACD by binding with CD1a molecules on the surface of Langerhans cells. Essentially, by binding with CD1a, these chemicals became "visible" to T cells, prompting the immune system to respond.
"We identified several compounds that can be recognized by T cells through CD1a, some of which are known allergens," de Jong explained. "Consumers should be able to see these compounds on the ingredient list, although under several different names."
However, she also emphasized that "it is too early to advise consumers based on our findings." Rather, she noted, "the study paves the way for follow up studies to confirm the mechanism in allergic patients, and to design inhibitors of the response."
