Published September 22, 2015

IL-9-producing mucosal mast cells (MMC9 cells) play a key role in amplifying allergic response to ingested food. 

This key finding, from a mouse study led by Yui-Hsi Wang, PhD, appeared online Sept. 22, 2015 in the journal Immunity. Insights from the study eventually could lead to a blood test to identify children at highest risk of anaphylactic shock triggered by the immune antibody IgE (immunoglobulin E).

MMC9 cells produce large amounts of interleukin 9 (IL-9), which amplifies shock response. Prior to this study, the key cellular source of IL-9 was unknown. 

“Our study suggests that although you need to have some level of IgE to trigger a food allergy response, you also have to produce MMC9 cells to get a severe response and anaphylaxis,” Wang says. “Without these cells you will not get severe food allergies.”

Peanuts, shellfish and a host of other foods can prompt the immune systems of some children to surge out of control. Without immediate intervention, the reaction can lead to diarrhea, hypothermia, respiratory distress, and shock.

About 40 percent of children have some IgE-associated food sensitivity, but only 8 percent of those children develop the severe reactions that can lead to shock, Wang says.

To verify that MMC9 cells were fueling severe allergic reactions, researchers treated the mice with an antibody that eliminated the cells. This resulted in decreased food allergy symptoms. When the team transferred MMC9 cells back into the same mice, the animals resumed exhibiting symptoms.

Researchers further linked this pathway to humans by analyzing small intestine biopsy samples from food allergy patients. The team found significantly increased expression of the IL-9 genetic transcript and other related transcripts.

Now the researchers are searching for the human equivalent of the MMC9 cells. If successful, their work ultimately may improve treatments to control dangerous food allergies.