Researchers developed chimeric allergen receptor Treg cells (CAlleR Tregs) that suppress birch pollen–driven allergic asthma in mice, according to a study in the Journal of Experimental Medicine. Led by investigators at Lausanne University Hospital and the University of Lausanne, with Center for Human Immunology Lausanne, the work adapted a CAR T-cell-inspired strategy to redirect regulatory T cells toward a soluble allergen. In sensitized mouse models, the engineered Tregs reduced or prevented asthma symptoms tied to type 2 immune responses. The paper positions the platform as a potential durable immunomodulation strategy, particularly for severe allergy patients where conventional allergen immunotherapy is not recommended. The authors describe the study as proof-of-concept and preclinical evidence supporting broader applications across different allergies.