Joiner K A, Schweinle J E
Laboratory of Parastic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892.
J Immunol. 1989 May 1;142(9):3164-70.
We examined the fate of C component C3 on the surface of Salmonella typhimurium during ingestion by human neutrophils. Initial experiments showed that C3 fragments and C3-acceptor complexes were the major serum ligands which were surface iodinated by canine myeloperoxidase on serum-incubated rough and smooth isolates of S. typhimurium. In contrast, labeled C3 was not identified when the same organisms were ingested by neutrophils in the presence of 125I-Na, a situation previously shown to iodinate particulate targets via the neutrophil myeloperoxidase-halide-H2O2 system. Pretreatment of neutrophils before phagocytosis with the lipid-soluble protease inhibitor diisopropylfluorophosphate (DFP), but not with other protease inhibitors (p-nitrophenylguanidinobenzoate, leupeptin, pepstatin), substantially blocked proteolysis of 125I-C3 on S. typhimurium strain RG108 during ingestion by neutrophils. Purification of neutrophil phagosomes containing S. typhimurium-bearing 125I-C3 showed that DFP but no other protease inhibitors blocked proteolysis of 125I-C3 within phagosomes. Iodinated C3-acceptor complexes were identified by immunoprecipitation from the detergent-insoluble fraction of phagosomes prepared from DFP-treated cells ingesting S. typhimurium in the presence of 125I-Na. These results show that C3 fragments on the surface of S. typhimurium are the major serum ligands which are halogenated and degraded by proteolysis during phagocytosis by human neutrophils, and suggest that the majority of proteolysis on the ingested target occurs within the neutrophil phagosome.
我们研究了人中性粒细胞吞噬鼠伤寒沙门氏菌过程中，C 成分 C3 在其表面的命运。初步实验表明，C3 片段和 C3 受体复合物是主要的血清配体，它们在血清孵育的鼠伤寒沙门氏菌粗糙型和平滑型菌株表面被犬髓过氧化物酶进行表面碘化。相比之下，当在 125I-Na 存在的情况下中性粒细胞吞噬相同细菌时，未鉴定出标记的 C3，此前已证明这种情况下会通过中性粒细胞髓过氧化物酶 - 卤化物 - H2O2 系统对颗粒靶标进行碘化。用脂溶性蛋白酶抑制剂二异丙基氟磷酸酯（DFP）而非其他蛋白酶抑制剂（对硝基苯基胍基苯甲酸、亮抑酶肽、胃蛋白酶抑制剂）在吞噬作用前预处理中性粒细胞，可在很大程度上阻断中性粒细胞吞噬期间鼠伤寒沙门氏菌菌株 RG108 表面 125I-C3 的蛋白水解。对含有携带 125I-C3 的鼠伤寒沙门氏菌的中性粒细胞吞噬体进行纯化显示，DFP 而非其他蛋白酶抑制剂可阻断吞噬体内 125I-C3 的蛋白水解。通过免疫沉淀从用 DFP 处理的细胞在 125I-Na 存在下吞噬鼠伤寒沙门氏菌制备的吞噬体去污剂不溶部分中鉴定出碘化的 C3 受体复合物。这些结果表明，鼠伤寒沙门氏菌表面的 C3 片段是主要的血清配体，在人中性粒细胞吞噬过程中会被卤化并通过蛋白水解降解，这表明摄入靶标的大部分蛋白水解发生在中性粒细胞吞噬体内。
