Weizmann Scientists Find How the Body Learns to Tolerate Food, Opening Door to New Allergy Treatments

The team identified a network of immune cells that allows the body to eat safely while staying alert to real dangers like infection.

By Shula Rosen

Researchers at Israel’s Weizmann Institute of Science have uncovered how the immune system learns to treat food as harmless rather than as a threat — a finding that could lead to new ways to prevent food allergies and related diseases.

The study, published in Nature, was led by Dr. Ranit Kedmi of the institute’s Systems Immunology Department. Her team identified a network of immune cells that allows the body to eat safely while staying alert to real dangers like infection.

Kedmi explained that this “oral tolerance” begins developing before birth, when a fetus is exposed to traces of food molecules from the mother’s diet. It continues through breastfeeding, early eating, and contact with beneficial gut bacteria.

Scientists once thought that a type of immune cell called a dendritic cell decided whether to attack or tolerate new substances. But Kedmi’s team found that another, much rarer cell type—known as ROR-gamma-t cells—actually starts the tolerance process.

When the researchers disabled these cells in mice, the animals quickly developed food allergies.

The team showed that these cells coordinate signals across several other types of immune cells, creating a chain reaction that prevents the body from attacking food.

If the system encounters an infection, however, it temporarily suspends tolerance so the immune system can fight off the intruder.

Kedmi likened the process to “two neighboring countries with a peace agreement.” If one side fires, she told The Jerusalem Post, “the other responds immediately, but when calm returns, the peace is restored.”

The discovery helps explain why the immune system can remain both peaceful and vigilant. It could also shed light on what goes wrong in disorders such as celiac disease, when the body mistakenly attacks its own tissues in response to food.

The research was carried out by Kedmi, master’s student Anna Rudnitsky, and colleagues at the Weizmann Institute in Rehovot.