A decade ago, a landmark U.K. clinical trial showed that early exposure to peanuts reduces the risk of developing peanut allergies in children. Now, researchers at Memorial Sloan Kettering Cancer Center (MSK) have identified the likely immune cells responsible: Thetis cells.
First described by MSK scientists in 2022, Thetis cells play a critical role in teaching the immune system to tolerate harmless food proteins, suppressing inflammatory responses. Findings published May 15 in Science reveal that these cells operate during a crucial early-life window to establish “oral tolerance” — preventing allergic reactions to foods like peanuts and eggs.
Thetis cells are a unique type of antigen-presenting cell that “educate” other immune cells on whether to attack or tolerate substances. Using genetically engineered mice, the research showed that a subset of Thetis cells in gut-draining lymph nodes takes up food proteins, then programs regulatory T cells to prevent allergic inflammation.
Importantly, Thetis cells are most abundant during early life, coinciding with the optimal window for developing food tolerance. Exposure to allergens after this period resulted in significantly weaker tolerance responses. This helps explain why early introduction of allergenic foods reduces allergy risk.
“We’ve shown there is a window for generating stronger tolerance, mediated by Thetis cells,” said study senior author Chrysothemis Brown, MD, PhD. She suggested this understanding could lead to new therapies that target Thetis cells to promote tolerance even outside early childhood.
Though the study used mice, Thetis cells are highly similar in humans, supporting current allergy guidelines encouraging early allergen introduction. Additionally, this research highlights why allergens introduced through the skin do not induce the same tolerance.
Beyond allergy prevention, the findings may also shed light on how early immune programming influences childhood cancer immunity.
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