Why We Itch
Stress has been found to activate the immune system in the skin of mice, causing them to itch.
The same likely holds true for humans, researchers say.
Itching remains somewhat mysterious. It is similar to pain in how it develops and plays out in our bodies. Because the skin is on the front lines against infection, it is a place where white blood cells attack invading bacteria and viruses. The immune cells in skin can overreact, though, causing inflammatory skin diseases such as dermatitis and psoriasis.
Stress is also known to increase odds of everything from the common cold to cancer.
Researchers figured stress could exacerbate skin disease by increasing the number of immune cells in the skin. To test the idea, they stressed out some mice. Indeed, more white blood cells were pumped into the skin. By blocking the function of two proteins that attract immune cells to the skin, called LFA-1 and ICAM-1, the scientists prevented the stress-induced increase in white blood cells in the skin.
Taken together, these data suggest that stress activates immune cells, which in turn are central in initiating and perpetuating skin diseases, the researchers conclude in the November issue of the American Journal of Pathology.
The work, funded by the German Research Foundation, was led by Petra Arck of Charité of the University of Medicine Berlin and McMaster University in Canada.