Reese Sven, Dalamani Grammatia, Kaspers Bernd
Institute for Animal Anatomy, Faculty of Veterinary Medicine, University of Munich, Germany.
Vet Res. 2006 May-Jun;37(3):311-24. doi: 10.1051/vetres:2006003. Epub 2006 Mar 9.
The lung is a major target organ for numerous viral and bacterial diseases of poultry. To control this constant threat birds have developed a highly organized lung-associated immune system. In this review the basic features of this system are described and their functional properties discussed. Most prominent in the avian lung is the bronchus-associated lymphoid tissue (BALT) which is located at the junctions between the primary bronchus and the caudal secondary bronchi. BALT nodules are absent in newly hatched birds, but gradually developed into the mature structures found from 6-8 weeks onwards. They are organized into distinct B and T cell areas, frequently comprise germinal centres and are covered by a characteristic follicle-associated epithelium. The interstitial tissue of the parabronchial walls harbours large numbers of tissue macrophages and lymphocytes which are scattered throughout tissue. A striking feature of the avian lung is the low number of macrophages on the respiratory surface under non-inflammatory conditions. Stimulation of the lung by live bacteria but not by a variety of bacterial products elicits a significant efflux of activated macrophages and, depending on the pathogen, of heterophils. In addition to the cellular components humoral defence mechanisms are found on the lung surface including secretory IgA. The compartmentalisation of the immune system in the avian lung into BALT and non BALT-regions should be taken into account in studies on the host-pathogen interaction since these structures may have distinct functional properties during an immune response.
肺是家禽众多病毒和细菌疾病的主要靶器官。为了应对这种持续的威胁，禽类发展出了高度组织化的与肺相关的免疫系统。在这篇综述中，描述了该系统的基本特征并讨论了其功能特性。在禽类肺中最突出的是支气管相关淋巴组织（BALT），它位于初级支气管和尾侧次级支气管的交界处。新孵化的禽类没有BALT小结，但会逐渐发育成从6 - 8周龄开始出现的成熟结构。它们被组织成不同的B细胞和T细胞区域，经常包含生发中心，并被一层特征性的滤泡相关上皮覆盖。副支气管壁的间质组织中含有大量散布于整个组织的组织巨噬细胞和淋巴细胞。禽类肺的一个显著特征是在非炎症条件下呼吸表面的巨噬细胞数量较少。活细菌而非多种细菌产物刺激肺会引发活化巨噬细胞的显著外流，并且根据病原体的不同，还会引发嗜异性粒细胞的外流。除了细胞成分外，在肺表面还发现了体液防御机制，包括分泌型IgA。在研究宿主 - 病原体相互作用时，应考虑禽类肺中免疫系统在BALT和非BALT区域的分隔，因为这些结构在免疫反应期间可能具有不同的功能特性。
