Mast cells are usually associated with the itch, inflammation and occasional acute anaphylaxis of an allergic reaction. But now it appears they serve a beneficial purpose as well: protecting the skin from sun damage or from irritants such as poison oak.
Working in the lab of Stephen Galli, a professor of pathology, microbiology and immunology in the School of Medicine, postdoctoral researcher Michele Grimbaldeston found that the damage caused by exposure to UV radiation or to urushiol, a toxin found in the leaves of some plants, is actually much worse without mast cells. At least, that’s the case in mice.
The discovery involved a bit of serendipity. Typically, researchers conducting similar studies have monitored the mice’s reactions only for the first 48 hours. Following a hunch, Grimbaldeston kept records for two full weeks.
After five days she noticed something unusual: the ears of the mice without mast cells were thicker than those of the normal mice, suggesting the accumulation of white blood cells. When she injected mast cells back into deficient mice, the inflammation was reduced. Grimbaldeston also identified the molecule responsible for limiting the ear swelling, interleukin-10.
Galli’s team previously demonstrated that mast cells also help break down the toxins in snake venom and bee stings. Next, the researchers plan to investigate whether they play a role in preventing skin cancer.
