ABSTRACT
Objective To investigate the alterations and phenotypes of dendritic cells, inflamma-tory monocytes and macrophages in immunocompetent mice during Pneumocystis murina ( P.murina) infec-tion for further analysis of the function of these cells during P.murina infection.Methods Wild type male C57BL/6 mice at age 6-8 weeks were randomly divided into two groups including the group with P.murina infection and the group receiving sham surgery.The mice without any intervention were used to set up the blank control group.The loads of P.murina strains in lung tissues of each mouse were quantified by TaqMan real-time fluorescence polymerase chain reaction after the infection.Histopathological examination was per-formed to evaluate the degree of inflammation in lung tissues.The numbers of dendritic cells, inflammatory monocytes and macrophages in lung tissues, peripheral blood and bone marrow samples, and the changes of inflammatory monocytes in spleen tissues were measured by flow cytometry analysis.The expression of major histocompatability complexⅡ(MHCⅡ), CX3C chemokine receptor 1 (CX3CR1) and CC chemokine re-ceptor 2 ( CCR2 ) by dendritic cells, inflammatory monocytes and macrophages in lung tissues during P.murina infection were analyzed by flow cytometry analysis.All of the data were collected one, two, three and four weeks after the corresponding treatments.Results The loads of P.murina strains in P.murina in-fected mice were elevated after two and three weeks infection, but decline at week 4 (P>0.05).Significant pathological changes including the alveolar destruction, inflammatory cell infiltration and thickened alveolar septum in mice with P.murina infection were observed under a microscope at week 3 and week 4.Compared to the sham surgery treatment group, the number of CD11c+CD11b+dendritic cells were increased in lung tissues, but decreased in blood samples during P.murina infection ( P0.05).The CD11c+CD11b+dendritic cells in lung tissues of mice with P.murina infection expressed high levels of MHCⅡand CX3CR1, and low levels of CCR2.The inflammatory monocytes in lung tissues of mice expressed high levels of CCR2, moderate levels of MHCⅡand low levels of CX3CR1 during P.murina in-fection.High levels of CX3CR1 and low levels of MHCⅡ and CCR2 were observed in macrophages from lung tissues of mice with P.murina infection.Conclusion Highly expressed CD11c+CD11b+dendritic cells and MHCⅡwere detected in lung tissues of mice during P.murina infection, indicating that CD11c+CD11b+dendritic cells were involved in the host defense against P.murina infection.