Roque R S, Imperial C J, Caldwell R B
Department of Anatomy and Cell Biology, University of North Texas Health Science Center, Fort Worth 76107-2699, USA.
Invest Ophthalmol Vis Sci. 1996 Jan;37(1):196-203.
Photoreceptor degeneration is accompanied by the invasion of phagocytic cells into the outer retina of Royal College of Surgeons (RCS) rats. Previous studies suggested that these mononuclear phagocytes were blood-borne macrophages and not retinal pigment epithelial cells nor Müller glia. Thus, immunospecific markers were used to identify these cells and to determine their distribution in the dystrophic retina.
Retinas from RCS and control (RCS-rdy+) rats were processed for immunocytochemistry using antibodies against phosphotyrosine, which labels both microglial cells and peripheral macrophages, and ED2, which labels peripheral macrophages only. As a positive control to demonstrate ED2-labeling of peripheral macrophages that enter the retina during injury, experiments were performed using needle-punctured Long Evans rat retinas.
In normal animals, process-bearing, phosphotyrosine-reactive cells were restricted to the inner retinal layers and the outer plexiform layer. In early dystrophic retinas, phosphotyrosine-reactive cells also were observed in the outer retinal layers. The number of phosphotyrosine-labeled cells in the outer retina increased substantially in later stages of dystrophy. ED2-reactive cells were observed in normal or dystrophic retinas only after needle puncture.
These findings suggest that phagocytic cells during the early stages of dystrophy in RCS rat retinas are derived from resident microglial cells, not from peripheral macrophages. The migration of microglial cells into the outer retina when photoreceptor cells begin to degenerate further suggests that they may play a major role in photoreceptor cell death in the dystrophic retina.
在皇家外科学院（RCS）大鼠中，光感受器变性伴随着吞噬细胞侵入视网膜外层。先前的研究表明，这些单核吞噬细胞是血源性巨噬细胞，而非视网膜色素上皮细胞或穆勒胶质细胞。因此，使用免疫特异性标志物来识别这些细胞，并确定它们在营养不良视网膜中的分布。
使用针对磷酸酪氨酸的抗体（该抗体可标记小胶质细胞和外周巨噬细胞）以及仅标记外周巨噬细胞的ED2抗体，对RCS大鼠和对照（RCS-rdy+）大鼠的视网膜进行免疫细胞化学处理。作为阳性对照，以证明在损伤期间进入视网膜的外周巨噬细胞的ED2标记，使用针刺朗伊 Evans 大鼠视网膜进行实验。
在正常动物中，带有突起的、磷酸酪氨酸反应性细胞局限于视网膜内层和外网状层。在早期营养不良的视网膜中，在外层视网膜中也观察到了磷酸酪氨酸反应性细胞。在营养不良的后期，外层视网膜中磷酸酪氨酸标记的细胞数量大幅增加。仅在针刺后，在正常或营养不良的视网膜中观察到了ED2反应性细胞。
这些发现表明，RCS大鼠视网膜营养不良早期的吞噬细胞来源于常驻小胶质细胞，而非外周巨噬细胞。当光感受器细胞开始进一步退化时，小胶质细胞迁移到外层视网膜，这进一步表明它们可能在营养不良视网膜中的光感受器细胞死亡中起主要作用。
