Twigg H L
Division of Pulmonary and Critical Care Medicine, Indiana University Medical Center, Indianapolis 46202, USA.
J Thorac Imaging. 1998 Oct;13(4):221-33. doi: 10.1097/00005382-199810000-00003.
The lung is constantly exposed to invading particulate matter and potential pathogens. To cope with this pressure, the lung has evolved a sophisticated, multitiered defense mechanism designed to clear offending agents while inducing a minimum amount of concomitant inflammation. Mechanical defense mechanisms first attempt to remove material physically from the tracheobronchial tree. Particulate matter and pathogens that circumvent this first line of defense are ingested by resident and recruited phagocytes in the lower respiratory tract and alveoli. If phagocytic defenses are impaired or overwhelmed, specific immune mechanisms become operational and lead to the generation of delayed-type hypersensitivity (granulomatous), cytotoxic, and humoral (antibody) responses. Congenital or acquired impairment of pulmonary host defenses can occur at any of these steps. Impairment of a particular component of pulmonary host defense is usually associated with a characteristic spectrum of infectious and noninfectious pulmonary complications. Thus, understanding all the components of pulmonary host defense and how to evaluate them will greatly aid the physician who cares for immunocompromised patients with lung disease.
肺不断暴露于入侵的颗粒物和潜在病原体中。为应对这种压力，肺进化出了一种复杂的多层防御机制，旨在清除有害因子，同时引发最少的伴随炎症。机械防御机制首先试图从气管支气管树中物理性地清除物质。绕过第一道防线的颗粒物和病原体被下呼吸道和肺泡中的驻留及募集的吞噬细胞吞噬。如果吞噬防御受损或不堪重负，特异性免疫机制就会发挥作用，并导致迟发型超敏反应（肉芽肿性）、细胞毒性和体液（抗体）反应的产生。肺宿主防御的先天性或后天性损害可发生在这些步骤中的任何一步。肺宿主防御特定成分的损害通常与一系列特征性的感染性和非感染性肺部并发症相关。因此，了解肺宿主防御的所有成分以及如何评估它们，将极大地帮助照顾患有肺部疾病的免疫功能低下患者的医生。
