眼表面的防御机制

<title>Defense mechanism of ocular surface

眼表面持续暴露于各种应急状态。为了保护眼表面的完整性并维持角膜的透明状态 ,眼表面将动用多种防御机制。这些防御机制包括 :固有的解剖学屏障、分泌某些化学性杀菌物质和细菌裂解物质 ,如溶菌酶和乳铁蛋白 ,局部分泌Ig A抗体 (s Ig A) ,局部免疫活性细胞反应和局部特异性分子的表达 ,如细胞因子和 Fas配体。眼表在睁眼和闭眼 2种状态下使用 2种完全不同的防御策略。长时间闭眼将导致泪膜组成、起源和代谢的显著改变。这些改变包括 s Ig A、分泌小片、补体成分和炎症介质水平的增高 。

<Abstrcat>The outer surface of the eye is constantly exposed to a wide array of stress conditions. To protect the integrity or the ocular surface and to retain corneal transparency, a number of defense mechanisms have evolved. These defenses include intrinsic anatomic barriers, secretion of certain chemical bacteriostatics and bacteriolytics such as lysozyme and lactoferrin, local secretary IgA (sIgA) antibody secretion, local immunocompetent cellular responses, and local molecular expressions such as cytokines and Fas ligand. Ocular surface utilizes distinctly two different strategies in open and closed eye conditions. Prolonged eye closure will results in a profound change in the composition, origins and turn over of the tear film. These changes include a marked increase in the level of sIgA, secretary component, complement components and inflammatory mediators as well as the recruitment of polymorphonuclear neutrophil into the tear film.