Sudden acquired retinal degeneration syndrome (SARDS) in dogs is proposed to have an immune-mediated etiology. However, there is conflicting evidence regarding the presence of antiretinal antibodies, as assessed by western blotting, in the serum of SARDS patients. Because of the possibility that antibodies recognize only conformational epitopes, we hypothesized that a more sensitive method to investigate circulating retinal autoantibodies in SARDS is immunofluorescence. Sera from 14 dogs with early SARDS, and 14 age- and breed-matched healthy control dogs were screened for circulating antiretinal IgG, IgM, IgE and IgA using indirect immunofluorescence on lightly fixed frozen sections of normal canine retina. Controls without canine serum were also performed. A nuclear counterstain was used to identify cellular retinal layers. Images were obtained using a fluorescent microscope, and 2-3 separate masked observers graded retinal layers for fluorescence staining intensity using a 0-3 scale. Total circulating IgG and IgM was assessed by radial immunodiffusion. Statistical analysis was performed using 2-way ANOVA, paired 2-tailed student's t-test and correlation analysis. Intensity of IgG staining of photoreceptor outer segments was significantly higher using serum from dogs with SARDS compared with healthy controls in 2/3 observers (P < 0.05). Intensity of IgM staining throughout the retina was higher in SARDS dogs compared to matched healthy controls (P < 0.0001), although no specific retinal layer was statistically significant. There were no differences in staining intensity for IgE or IgA. Dogs with SARDS had a comparably lower circulating IgG and higher IgM than healthy controls (P = 0.01 and 0.001 respectively) and IgG and IgM were negatively correlated (r = -0.69, P = 0.007). Despite having decreased serum IgG compared with healthy controls, circulating IgG in dogs with SARDS binds photoreceptor outer segments to a greater extent. Dogs with SARDS have a relatively higher circulating IgM than matched healthy controls. The pathogenic nature of these antibodies is unknown.

中文翻译：

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间接免疫荧光法检测患有突然获得性视网膜变性综合征的犬中循环抗视网膜抗体：病例对照研究。

犬突然获得性视网膜变性综合征（SARDS）被认为具有免疫介导的病因。然而，有证据表明，SARDS患者血清中存在抗视网膜抗体，如通过蛋白质印迹法所评估的。由于抗体可能仅识别构象表位，因此我们假设研究SARDS中循环视网膜自身抗体的更灵敏方法是免疫荧光。使用间接免疫荧光法在正常犬视网膜的轻度固定冰冻切片上，筛选了14只患有SARDS早期狗以及14只年龄和品种匹配的健康对照狗的血清中的循环抗视网膜IgG，IgM，IgE和IgA。还进行了无犬血清的对照。使用核复染色来识别细胞视网膜层。使用荧光显微镜获得图像，并使用2-3个独立的蒙版观察者对视网膜层进行分级，以使用0-3比例缩放荧光染色强度。通过放射免疫扩散评估总循环IgG和IgM。统计分析使用2通方差分析，配对的2尾学生t检验和相关分析进行。在2/3的观察者中，使用SARDS的狗的血清与健康对照组相比，感光器外部节段的IgG染色强度明显更高（P <0.05）。尽管没有特定的视网膜层在统计学上具有统计学意义，但与匹配的健康对照组相比，SARDS狗中整个视网膜的IgM染色强度更高（P <0.0001）。IgE或IgA的染色强度没有差异。患有SARDS的狗的循环IgG和IgM均比健康对照组低（分别为P = 0.01和0.001），并且IgG和IgM呈负相关（r = -0.69，P = 0.007）。尽管与健康对照组相比，血清IgG降低了，但患有SARDS的狗体内的循环IgG在更大程度上结合了感光体的外部片段。患有SARDS的狗的循环IgM高于匹配的健康对照组。这些抗体的致病性未知。