RETINAL LEUKOCYTE BEHAVIOR IN EXPERIMENTAL AUTOIMMUNE UVEORETINITIS OF RATS

In vivo retinal leukocyte behavior in the experimental autoimmune uveo retinitis (EAU) of rats was investigated using acridine orange digital fluorography. The technique employed high resolution images obtained from a scanning laser ophthalmoscope (SLO) subsequent to staining with the fluorescent nuclear dye, acridine orange. Two weeks after immuniz ation with synthetic peptides of retinal soluble antigen (S-Ag), acrid ine orange was intravenously injected, and fundus images were generate d by SLO. Many rolling leukocytes were observed along the venous walls as slowly moving fluorescent dots; moreover, leukocytes infiltrating into the vitreous cavity were also noted especially over the retinal v eins, but not over the retinal arteries. In addition, major retinal ve ssels were significantly dilated. The diameters of the retinal veins a t a distance of 1 disc diameter away from the center of the optic disc were 49.8+/-4.5 mu m for the normal rats and 88.2+/-3.6 mu m for the EAU rats, respectively (P < 0.001). Similarly, the diameters of retina l arteries were 32.6+/-3.7 mu m for the normal rats, 53.8+/-1.5 mu m f or the EAU rats, respectively (P < 0.01). The dilation was more promin ent in the veins than in the arteries. These results suggest that it i s possible to Visualize the retinal involvement of EAU in vivo, The re sults also suggest that leukocyte-endothelial interaction and extravas cular infiltration in the retinal venous vasculature may play signific ant roles in the early stages of posterior segment inflammation in EAU . (C) 1997 Academic Press Limited.