Certain Proteins May Help Prevent Food Allergies

In food allergies, the body’s defense system, called the immune system, reacts to harmless food as if it were a threat. To understand why this happens, scientists first need to know how the body develops a tolerance to a food. A new study showed that certain parts of dietary proteins normally act as signals that foods are safe.

Researchers found seven different sensors in specialized immune cells in the mouse gut. The sensors reacted to proteins in mouse chow. Five of the sensors were activated by corn protein found in mouse chow. One was activated by a wheat protein, and the other by a soybean protein.

The sensors only detected certain parts of the proteins, called epitopes. The most frequently recognized epitope was on a corn protein. The specialized cells that recognized the corn protein first appeared when the mice were four weeks of age. This was about the same time that the mice first ate the food. The cells sent signals to other immune cells not to attack the food protein.

Scientists are just starting to understand how the body builds tolerance to food. “For a long time, we thought food tolerance simply meant the immune system was ignoring the foods we eat—that is to say that tolerance is the absence of allergy,” says Dr. Elizabeth Sattely of Stanford University, who co-led the study. “But we now know that tolerance is active and adaptive behavior. Certain cells in our intestines survey the foods we eat, looking for specific proteins. When found, the cells signal the immune system that the food is safe.”