摘要目的：回顾性探讨仅有补体 C3沉积的毛细血管内增生性肾炎患儿的临床特点及疾病转归，深入认识补体 C3在肾损伤中的作用。方法选择2010年11月至2014年10月首都医科大学附属北京儿童医院肾脏病理表现为毛细血管内增生性肾炎但免疫荧光仅有 C3沉积的肾小球肾炎患儿为研究对象（为避免假阳性，补体 C3≥2﹢为纳入标准），回顾性分析患儿临床表现、实验室检查以及治疗、预后和病理改变，并结合文献复习，总结此类患儿的临床特点及转归规律。结果共有11例患儿病理表现为毛细血管内增生性肾炎，且其免疫荧光仅有补体 C3沉积（≥2﹢）。11患儿中9例以急性肾炎综合征起病（81.8%），2例患儿表现为反复发作性肉眼血尿（18.2%）。其中7例患儿临床诊断为链球菌感染后肾炎（63.6%）。11例患儿临床表现相对较重，补体 C3均显著低于正常值（100.0%）。光镜均表现为毛细血管内增生性肾炎，电镜提示免疫复合物主要在内皮下、上皮下或系膜区沉积。分别给予相应治疗，随访7个月~3年3个月，所有患儿目前预后良好。结论在毛细血管内增生性肾炎仅伴补体 C3沉积的患儿中链球菌感染是常见诱因，部分患儿与链球菌感染后肾炎有相似的临床经过，但此部分患儿临床表现相对较严重，认为病理中不伴 IgG 的单纯补体 C3沉积现象可能与不同补体活化机制有关。

abstractsObjective To study the patients' clinical characteristics and prognosis when only C3 deposition exists in endocapillary proliferative glomerulonephritis and try to understand deeply the role of C3 in kidney damage deeply. Methods The patients who were diagnosed with endocapillary proliferative glomerulonephritis but only had C3 deposited in immunofluorescence(to avoid false positive,C3≥2 ﹢ was included)were selected from Beijing Children's Hospital Affiliated to Capital Medical University during November 2010 to October 2014. Their clinical manifestations,la-boratory examinations,treatments,prognosis,and pathological changes were analyzed,and literature review was performed. Their clinical characteristics and prognosis were summarized. Results There were 11 patients diagnosed with endocapil-lary proliferative glomerulonephritis which had only C3 deposition(≥2 ﹢ ). Nine of them had onset with acute nephritis syndrome(81. 8% ),and 2 cases presented recurrent paroxysmal gross hematuria(18. 2% ). Seven cases were diagnosed with acute post streptococcal glomerulonephritis(63. 6% ). Eleven cases' clinical manifestations were relatively severe, and the complement C3 was significantly lower than the normal(100. 0% ). Their light microscope showed capillary proli-ferative glomerulonephritis,and the electron microscope showed the immune complexes were deposited in the endothelium,the epithelium or the mesangial area. The patients received corresponding treatment respectively,and all the patients had good prognosis during following up of 7 months up to 39 months. Conclusions Streptococcus infection is a common cause in endocapillary proliferative glomerulonephritis with only C3 deposition. The clinical manifestations of some children are similar to post streptococcal glomerulonephritis but relatively severe. Only deposition of C3 without IgG may be involved in another complement activation mechanism.