灭活A组链球菌全菌体抗原诱导风湿性心脏炎的可行性

Feasibility of Rheumatic Carditis Induced by Inactivated Whole Cell Antigen of Group A Streptococcus

【目的】探讨以Lewis大鼠为实验对象,用皮下注射灭活A组链球菌全菌体抗原的方法诱导风湿性心脏炎的可行性。【方法】复活并繁殖A组β溶血性链球菌,细菌用40g/L甲醛液灭活。实验大鼠分为3组:对照组(4只)、模型A组(8只)、模型B组(5只)。模型A组大鼠后足垫注射灭活A组链球菌全菌体抗原/完全弗氏佐剂(CFA)混合液。初次免疫后第1周腹部皮下再次注射上述抗原1次,第3周(第21天)解剖动物。模型B组大鼠初次免疫同模型A组,第1、2、3周腹部皮下重复接受注射上述抗原,第6周(第42天)解剖动物。对照组大鼠后足垫注射生理盐水/CFA混合液,第3周(第21天)解剖动物。观察动物的体质量、足关节炎症程度、抗心肌抗体IgG吸光度,以及心脏、肾脏、肺脏和足关节的病理组织切片。【结果】模型A组大鼠的抗心肌抗体IgG吸光度免疫前、免疫后第2周、第3周分别为0.13(S=0.03)、0.24(S=0.06)和0.27(S=0.03),提示HRAbIgG抗体浓度从免疫后第2周开始呈上升趋势。免疫后第3周,模型A组8只大鼠中有3只心肌间质出现少量的灶性炎症细胞浸润,未观察到心瓣膜炎症变化。模型B组大鼠5只大鼠中有4只心肌间质小血管旁出现较明显的灶性炎症细胞浸润,其中2只观察到心瓣膜炎症。【结论】以Lewis大鼠为对象,使用皮下注射灭活A组链球菌的方法,可以诱发大鼠发生心脏炎。

[ Objective ] To investigate the feasibility of rheumatic carditis in Lewis rats induced by formalin-inactivated whole cell antigen of group A streptococcus （GAS） by subcutaneous injection. [Methods] GAS were cultured in liquid media of heartbrain infusion and inactivated by 10% formalin. Seventeen Lewis rats were divided into control group （4 Lewis rats）, model A group （8 Lewis rats）, and model B group （5 Lewis rats）. Lewis rats in model A group were injected in post-foot pads with the mixed solution of formalin-inactivated GAS suspension and complete Freund＇s adjuvent （CFA） （0.2 mL per rat）, repeated subcutaneous immunization was done in rat bellies after 1 week, and they were sacrificed 3 weeks after the initial immunization. Model B group received initial immunization, as model A group, with repeated subcutaneous immunization in their bellies after 1, 2, and 3 weeks, and they were sacrificed 6 weeks after the initial immunization. Control group was dealt with the emulsification of normal saline blended with CFA as model A group. Body weight, podarthritis, absorbance of anti-myocardial antibody （IgG） and pathological changes of heart, kidney, lung, and podarthrum were observed. [Resuhs]Absorbencies of anti-myocardial antibody （IgG） in model A group rats were 0.13 （S = 0.03）, 0.24 （S = 0.06）, and 0.27 （S = 0.03） before immunization and in the 2nd and 3rd week after the initial immunization, respectively, which suggested increasing of concentration of heart reactive antibody IgG （HRAb IgG） detected by enzyme-linked immunosorbent assay （ELISA） in the 2nd week after immunization. Focal inflammatory cell infiltration was observed in myocardial interstitial in 3 of 8 rats in model A group. In model B group, more focal inflammatory cell infiltration was presented in 4 rats and valvulitis was observed in 2 rats. [Conclusion] Carditis might be induced by immunization of formalin-inactivated GAS in Lewis rats.