RT Book, Section A1 Britto, Clemente J. A1 Dela Cruz, Charles S. A2 Grippi, Michael A. A2 Antin-Ozerkis, Danielle E. A2 Dela Cruz, Charles S. A2 Kotloff, Robert M. A2 Kotton, Camille Nelson A2 Pack, Allan I. SR Print(0) ID 1194946954 T1 Innate and Adaptive Immunity in the Lung T2 Fishman’s Pulmonary Diseases and Disorders, 6e YR 2023 FD 2023 PB McGraw-Hill Education PP New York, NY SN 9781260473988 LK accessmedicine.mhmedical.com/content.aspx?aid=1194946954 RD 2024/03/29 AB The lung is constantly exposed to environmental nonpathogenic and pathogenic moieties in ambient air. These moieties include infectious agents or their products, allergens, irritants, and other inhaled antigens capable of eliciting an immune response. The first line of defense in the interactions between environmental exposures and the respiratory tract is a barrier composed of a mucus layer, airway surface liquid, cilia, and the airway epithelium. This barrier is supported by a complex network of immune defense mechanisms that are both innate and adaptive.1,2 The immune response must recognize and react to a wide variety of stimuli. It must also identify and eliminate unwanted pathogens to keep pulmonary structures free from infection. On the other hand, this response must be closely regulated to maximize pathogen clearance while minimizing excessive inflammation and tissue injury. An adequate balance between immune response and its resolution is essential to preserve normal pulmonary architecture, especially the highly vascular and fragile alveolar epithelial surface required for gas exchange. The disruption of these lung protective mechanisms contributes to the pathogenesis of many pulmonary diseases. Therefore, understanding innate and adaptive immune responses in the lung is important to understand the pathophysiology and to improve the management of respiratory diseases. These anatomic and immune defenses are reviewed below.