CONTEXT: Asthma has been defined as a chronic inflammatory disorder of the airways that is associated with recruitment of inflammatory cells and the clinical development of wheezing, shortness of breath, chest tightness, and cough. Asthma is a major public health issue. It affects 5% of the United States population and accounts for 2 million emergency department visits, 470,000 hospitalizations, and 4500 deaths annually. OBJECTIVE: To review the pathophysiology and characteristic pathologic patterns of this disease and discuss the possible mechanisms of production of the lesions. DATA SOURCES: We searched the literature using MEDLINE and OVID. We also searched related conference abstracts and bibliographies of selected studies. CONCLUSIONS: There has been a significant evolution in our understanding of asthma. Specific pathways and mechanisms in recent years have been studied; however, numerous mediators and cell receptors have raised new questions that remain to be answered.
