表达GFP的重组减毒鼠伤寒沙门氏菌体内感染抗原呈递细胞的动态变化

目的：阐明重组减毒鼠伤寒沙门氏菌在体内早期感染抗原呈递细胞(APC)的动态变化规律。方法：用一定剂量的表达绿色荧光蛋白(GFP)的重组减毒鼠伤寒沙门氏菌X4550(pY．AG-FP)口服接种BALB／c小鼠。3d后，取腹腔巨噬细胞培养24h，用荧光显微镜观察。另以该细菌静脉注射小鼠，于感染后3、6和12h，制备脾脏、肝脏低浮密度细胞。用流式细胞术检测巨噬细胞和树突状细胞的感染率。结果：巨噬细胞感染X4550(pYAGFP)的百分率，腹腔中约为50％，肝脏和脾脏中约为20％～40％。树突状细胞感染X4550(pYAGF、P)的百分率，脾脏中约为4％～10％，肝脏中约为10％～20％。巨噬细胞的吞噬能力明显高于树突状细胞。结论：感染早期，重组减毒鼠伤寒沙门氏菌在体内已被APC所摄取，为诱导有效的免疫应答提供了先决条件。

In vivo dynamic changes of antigen presenting cells infected with recombinant attenuated Salmonella typhimurium expressing green fluorescent protein

AIM: To clarify in-vivo early dynamic changes of antigen-presenting cells (APCs) infected with recombinant attenuated Salmonella typhimurium. METHODS: BALB/c mice were orally infected with recombinant attenuated Salmonella typhimurium expressing green fluorescent protein (GFP) X4550 (pYAGFP). Peritoneal macrophages were taken out 3 days after infection, cultured for 24 hours, and observed under the fluorescent microscope. Moreover, BALB/c mice were also infected intravenously with X4550 (pYAGFP) and low density cells (LDCs) were isolated and prepared from mouse spleen and liver 3,6 and 12 hours after infection. Infection rates of macrophages and dendritic cells (DCs) were analyzed by flow cytometry. RESULTS: About 50% peritoneal macrophages were X4550 (pYAGFP) positive. Infection rates of macrophages in spleen and liver were about 20%-40%. As for the DCs, the infection rates in spleen and liver were about 4%-10% and 10%-20%, respectively. CONCLUSION: Recombinant attenuated Salmonella can be captured by APCs in-vivo in early infection, which provides a precondition for inducing effective immune responses.