Friday, September 7, 2007

Mast Cells: The Good, Bad and Ugly

Stanford researchers have found that mast cells, known for triggering the itch and inflammation in allergy attacks, can also calm down the flare-ups. These findings were published in the September online version of Nature Immunology.

The new findings reveal that, in mice, mast cells help decrease skin damage over time from sun exposure or from poison oak by releasing the immune-suppressing molecule, interleukin-10 (IL-10), the same brilliant anti-inflammatory tissue repair interleukin released by our bodies after prolonged exercise stimulates the release of the tissue breakdown proinflammatory interleukins, IL-6.

The findings contradict mast cells' reputation for being the trigger-happy gunslinger in an allergic reaction. Located just beneath the skin and in the loose connective tissue throughout the body, mast cells lie in wait for intruders. Packed with granules containing inflammation-inciting molecules such as histamine, they sometimes react to non-threatening trespassers, such as pollens or plant oils. Mast cell response to pollen can cause excessive tearing and eyeball itching that drives thousands of folks crazy every spring.

The ugly side: over zealous mast cell confrontations can cause allergic reaction and, in extreme cases, the life-threatening overreaction of anaphylaxis seen in bee-sting or peanut allergies.

"The fact that one sees the mast cell playing a role in resolving inflammation is surprising," said Juan Rivera, PhD, chief of the Molecular Inflammation section of the National Institute of Arthritis and Musculoskeletal and Skin Diseases. "All of the research thus far has focused on how quickly mast cells unleash inflammation rather than how they might mitigate it. I find it very intriguing finding that the mast cell plays this dual role."

The obvious question for our readers: does the human mast cell eventually release IL-10 to stop the ocular reaction to spring pollens if there is no pharmaceutical interference in the process?


Harry Robinson said...

Hey Ellen,

You must not have spring allergies or you would never suggest that those of us who do wait around for our mast cells to decide to release IL-10.

Keep bringing on the Patanol!

Ellen Troyer, MT MA said...

Hi Harry,

Good to hear from you.

I did not mean to suggest you give up the Patanol, which if memory serves you have in every car, lab coat, briefcase and jacket pocket you own during spring time. I just wondered, given this new science, if you could stick the allergic reaction out for just a few days if your mast cells would do an about face and stop the reaction on their own.

James Waugh, MD said...

Ellen, Are you talking about spontaneous resolution? If so, it does happen with spring allergies, but rarely.

Ellen Troyer, MT MA said...


Doesn't it make sense that there is always an explaination for spontaneous resolution that we don't yet have the knowledge to understand.

Knowing that mast cells can also calm down flare-ups under certain conditions could explain a lot, particularly knowing they release tissue repairing interleukin-10.