Ultrastructural pathology of experimental autoimmune uveitis: A Review

Experimental autoimmune uveitis (EAU), a disease induced in animals immunised at distant sites with retinal antigens, in conjunction with appropriate adjuvants, is a well recognised paradigm of various forms of human uveitis since many of the clinical and histopathological manifestations of the human disease can be closely mimicked in this model. Electron microscopy and other nonultrastructural morphological techniques have proven valuable tools in studying the pathology of EAU due to the highly organised and heterogeneous nature of the affected cells and tissues within the eye, namely the neural retina, retinal pigment epithelium and choroid. The role of various resident ocular immune cells including mast cells, dendritic cells, choroidal macrophages and retinal microglia in the induction and pathogenesis of EAU, is reviewed. In addition, the role of various effector cells in the inflammatory cell infiltrate, namely polymorphonuclear leukocytes, T cells and macrophages, and their interaction with retinal target cells is discussed. This review also considers the morphological changes which precede and accompany early inflammatory cell infiltration through the blood-ocular barrier which are of critical importance to initiation of the autoimmune process. In many ways EAU represents an ideal model for autoimmune diseases in general and especially for those involving the central nervous system. The precise microanatomical arrangement of the eye and its distinct blood-tissue barriers have allowed researchers studying EAU to precisely identify the target cells, pathways used by ingressing inflammatory cells and the nature of the effector cells in this disease.