IL13 and chronic obstructive pulmonary disease: Similarly, in COPD patients with blood eosinophil counts exceeding 300 cells/μL, a threshold often used to define ACO, treatment with dupilumab, a monoclonal antibody targeting IL-4/IL-13 signaling, resulted in fewer exacerbations, better lung function, improved quality of life, and reduced symptom burden compared to placebo [27].