The Dynamic Changes Of CD11C~+CD45RA~-Myeloid Dendritic Cells And CD11C~+CD45RA~+Plasmacytoid Dendritic Cells In The Mice Infected With Echinococcus Multilocularis

Objective: The purpose of this study is to observe the dynamic changes ofCD11C+CD45RA-myeloid dendritic cells (mDC) and CD11C+CD45RA+plasmacytoiddendritic cells (pDC) in the spleen and lymph nodes of Balb/c mice infected withechinococcus multilocularis (E.m). The dynamic level change of IL-12, IFN-γ secreted byspleen DC might reveal the role and mechanisms of dendritic cells in E.m infection.Methods:20mice were chosen randomly from80healthy female Balb/c mice to detectthe E.m infection rate. The other60mice were randomly divided into the experimentalgroup and the healthy control group，30mice in each group. Mice in the experiment groupwere injected intraperitoneally with0.2ml protoscolex suspension (about400protoscolex)，while the mice in the control group was injected intraperitoneally with equalamount of saline. At2d，8d，30d，90d，180d and360d after injection，5mice was killedeach time respectively in two groups. The spleen and lymph nodes were obtained sterilefor cell suspension with routine methods. Meanwhile， the count percentage ofCD11C+CD45RA-mDC，CD11C+CD45RA+pDC in spleen and lymph nodes were detectedby flow cytometry. Splenic DC were purified and cultured in vitro and then the levels ofIL-12, IFN-γ in the supernatant were measured by ELISA. Results (1) E.m vesicles wereinitial visible at90d after infected with E.m and in every lobe of liver at360d；(2) Thepercentage of splenic mDC and lymphnodes mDC were distinctly higher than controlgroup(P<0.01) at2d、8d、30d、90d、180d after infection. And it grew slowly through2dto90d，arrived the peak at90d，and then decreased quickly in the subsequent process untilat360d. The percentage of splenic mDC in experimental group did not have obviously difference compared with control group(p>0.05)，but the percentage of lymphnodes mDCwere significantly lower in experimental group（P<0.01.（3）The percentage of splenicmDC did not show obviously difference compared with control group（p>0.05）at2d afterinfection. No statistical difference were found in the percentage of lymphnodes mDCbetween experimental and control group（p>0.05）after2d、8d. The percentage of mDC inspleen and lymphnodes were sharply increased after30d，got to peak in90d，and thendecreased slowly，and still kept in higher level in experimental group at180d、360d afterinfection, which were significantly higher than control group（P<0.01）.(4) The mDC/pDCratios in spleen and lymph nodes in experimental group were higher than in the controlgroup in2d、8d、30d after infection，but lower than the control group in90d，180d，and360d after infection. The difference of mDC/pDC ratio in each period were statisticallysignificant in experimental group（P<0.05）.(5) The levels of IFN-γ and IL-12in splenicDC culture supernatant of mice infected with Em were higher than the control group(P<0.05). The levels rised at first and then declined following the infection time，whichreached at peak point in90d after infection. Conclusion In the early infection stage，immunological effect mediated by mDC was dominant. It could promote immuneresponse of cells and mediated immune protection. The mDC might play an important rolein the occurrence，development and clearance in early stage of alveolar hydatid. The pDCbecame a major role and could induce and keep the immune tolerance of human in themiddle-late infection stage. It could be conducive to the growth of the parasite in thehuman body and let the infection enter a chronic procedure. The secretion of IL-12andIFN-γ by DC might participate in the immune process and play an important immuneregulating role in enhancing the immunity of host and inhibiting the growth of hydatidafter Em infection.