Topic overview

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Asthma is characterized by episodic, largely reversible obstruction associated with Th2-mediated eosinophilic inflammation and IgE. Mast-cell mediators can produce bronchoconstriction, while edema and mucus contribute to airway narrowing; persistent disease may remodel the airway. COPD is generally less reversible and strongly associated with smoking. Neutrophils, macrophages, and CD8⁺ T cells contribute to tissue injury, while reduced elastic recoil, airway collapse, mucus, and fibrosis restrict airflow. The diseases also differ in steroid responsiveness: asthma is generally steroid-sensitive, whereas COPD has a more limited response. This preview frames the key mechanisms and therapeutic rationales; the full lesson develops their distinctions and clinical relevance in greater detail.