Researchers at Lausanne University Hospital, the University of Lausanne, and the Center for Human Immunology Lausanne reported preclinical evidence that chimeric allergen receptor (CAlleR) regulatory T cells can suppress allergic asthma in mice. The findings were published in the Journal of Experimental Medicine. The team engineered regulatory T cells to recognize a birch pollen allergen and showed reduced or prevented asthma symptoms in mice sensitized to the allergen. Lead author Yannick D. Muller, MD, PhD, said the study provides proof-of-concept that CAlleR Tregs can downmodulate birch pollen–induced airway inflammation. The report positions the approach as a potential new way to restore allergen tolerance, distinct from current allergen immunotherapy (AIT), which is not recommended for patients with severe asthma. The authors described the mechanism as redirecting immune regulation toward soluble antigens. While the work remains preclinical, it outlines a cellular strategy that could expand beyond one allergen and potentially address severe allergic asthma where existing options are limited.