Orikasa M, Matsui K, Oite T, Shimizu F
Department of Immunology, Niigata University School of Medicine, Japan.
J Immunol. 1988 Aug 1;141(3):807-14.
A single i.v. injection of a mAb 5-1-6 to rats was found to cause massive though transient proteinuria. This mAb 5-1-6, IgG1 was produced by immunization of BALB/c mice with collagenase-treated Wistar rat glomeruli and was highly organ and species specific. Immunoelectron microscopy using immunoperoxidase with the avidin-biotin complex and immunogold staining indicated mAb 5-1-6 to bind in vitro to the surface of glomerular epithelial foot processes, mainly to slit diaphragms. The recognized antigenic molecule was not susceptible to neuraminidase treatment and its Mr was about 51 kDa by immunoprecipitation. A one-shot i.v. injection of this mAb induced proteinuria in rats starting immediately, reaching the peak on day 8 (mean value of 150 mg/24 h), then gradually decreasing to normal level on day 18. The in vivo localization of administrated mAb 5-1-6 changed with time. Linear binding along glomerular capillary walls was observed 2 h after injection. However, 3 days later, it partially shifted to a fine granular pattern. The linear pattern disappeared and the size as well as intensity of the fluorescent granules decreased on day 12 to trace positive on day 18. Immunoelectron microscopy revealed the binding pattern of in vivo injected mAb 5-1-6 after 2 h to be similar to that in vitro. Three days later, injected mAb was observed within multivesicular bodies in glomerular epithelial cells as well as along the surface of foot processes and around slit diaphragms. Twelve days after injection, mAb along the surface of the foot processes and around slit diaphragms decreased but those in multivesicular bodies were observed more frequently. Rat IgG and C3 could not be detected throughout the period of observation. No histologic abnormalities were noted except for partial retraction of epithelial foot processes at the peak of proteinuria on day 8. This mAb thus provides a valuable means for examining the mechanism of proteinuria.
研究发现，给大鼠单次静脉注射单克隆抗体5-1-6会导致大量但短暂的蛋白尿。这种单克隆抗体5-1-6为IgG1，是用胶原酶处理过的Wistar大鼠肾小球免疫BALB/c小鼠产生的，具有高度的器官和物种特异性。采用抗生物素蛋白-生物素复合物免疫过氧化物酶和免疫金染色的免疫电子显微镜检查表明，单克隆抗体5-1-6在体外与肾小球上皮足突表面结合，主要是与裂孔隔膜结合。所识别的抗原分子对神经氨酸酶处理不敏感，通过免疫沉淀法测得其分子量约为51 kDa。单次静脉注射该单克隆抗体可使大鼠立即出现蛋白尿，在第8天达到峰值（平均值为150 mg/24 h），然后在第18天逐渐降至正常水平。注射的单克隆抗体5-1-6在体内的定位随时间变化。注射后2小时观察到沿肾小球毛细血管壁呈线性结合。然而，3天后，它部分转变为细颗粒状模式。线性模式消失，荧光颗粒的大小和强度在第12天减小，到第18天变为微量阳性。免疫电子显微镜显示，注射后2小时体内注射的单克隆抗体5-1-6的结合模式与体外相似。3天后，在肾小球上皮细胞的多囊泡体内以及足突表面和裂孔隔膜周围观察到注射的单克隆抗体。注射12天后，足突表面和裂孔隔膜周围的单克隆抗体减少，但在多囊泡体内观察到的单克隆抗体更频繁。在整个观察期间未检测到大鼠IgG和C3。除了在蛋白尿峰值的第8天上皮足突部分回缩外，未发现组织学异常。因此，这种单克隆抗体为研究蛋白尿的机制提供了一种有价值的手段。
