Bouvier G, Benoliel A M, Foa C, Bongrand P
INSERM U 387, Laboratoire d'Immunologie, Hôpital de Sainte-Marguerite, Marseille, France.
J Leukoc Biol. 1994 Jun;55(6):729-34. doi: 10.1002/jlb.55.6.729.
The fate of pathogens ingested by macrophages is dependent on phagosome acidification and fusion with different intracellular vesicles. Whereas the mode of particle recognition by the phagocyte seems the main determinant of phagosome-lysosome fusion, the influence of membrane reorganization, fusion events, and cell activation in phagosome acidification is not well known. We looked for a relationship between the nature of receptors involved in phagocytosis, phagosome acidification, and phagosome-lysosome fusion. Murine macrophage-like P388D1 cells were made to ingest sheep erythrocytes coated with immunoglobulin G (EIgG) or IgM and complement (EIgMC) or treated with glutaraldehyde and periodate (EGP). The following results were obtained: (1) As expected, the adhesion of the three particle types was differentially inhibited by monoclonal antibodies specific for Fc gamma RII and CD11b/CD18. (2) The phagosomes containing all three particle types displayed similar acidification kinetics with a pH decrease to 6 within the first 10 min after ingestion. (3) Only phagosomes containing EIgG or EIgMC were fused with peroxidase-loaded secondary lysosomes. (4) Coating EGP with IgG only partially restored fusion, even when the surface density of IgG was markedly higher than found on EIgG. It is concluded that phagosome acidification and fusion are regulated by different mechanisms. Also, the lack of fusion observed with EGP is not entirely accounted for by the absence of stimulation of suitable receptors on the phagocyte membrane, because it cannot be restored by providing such a stimulus.
巨噬细胞摄取的病原体的命运取决于吞噬体酸化以及与不同细胞内囊泡的融合。虽然吞噬细胞识别颗粒的方式似乎是吞噬体 - 溶酶体融合的主要决定因素，但膜重组、融合事件和细胞活化对吞噬体酸化的影响尚不清楚。我们探寻了参与吞噬作用的受体性质、吞噬体酸化和吞噬体 - 溶酶体融合之间的关系。使鼠类巨噬细胞样P388D1细胞摄取包被有免疫球蛋白G（EIgG）或IgM及补体（EIgMC）的绵羊红细胞，或用戊二醛和高碘酸盐处理的绵羊红细胞（EGP）。得到了以下结果：（1）正如预期的那样，三种颗粒类型的黏附被针对FcγRII和CD11b/CD18的单克隆抗体不同程度地抑制。（2）含有所有三种颗粒类型的吞噬体表现出相似的酸化动力学，摄取后最初10分钟内pH降至6。（3）只有含有EIgG或EIgMC的吞噬体与负载过氧化物酶的次级溶酶体融合。（4）用IgG包被EGP只能部分恢复融合，即使IgG的表面密度明显高于EIgG上的密度。得出的结论是，吞噬体酸化和融合受不同机制调节。此外，观察到的EGP缺乏融合现象不能完全归因于吞噬细胞膜上缺乏合适受体的刺激，因为提供这种刺激并不能恢复融合。
