[Echinococcus granulosus recombinant antigen B induced IDO expression in mouse bone marrow-derived dendritic cells in vitro]

Abstract

Objective: To observe the expression of indoleamine 2,3-dioxygenase (IDO) in mouse bone marrow-derived dendritic cells (DCs) after adding Echinococcus granulosus recombinant antigen B (rAgB) in vitro.

Methods: CD11c+ DCs generated from bone marrow precursor cells of C57BL/6 mice and cultured in the presence of recombinant mouse GM-CSF (rmGM-CSF). The morphology of DCs was observed by inverted microscope and scanning electronic microscope. The level of I-A/I-E, CD40, CD80, and CD86 on DCs were determined by flow cytometry. T cell proliferation induced by DCs were evaluated by using mixed lymphocyte reaction (MLR) assay. At day 6 post culture, the immature DCs were collected, and part of the immature DCs stimulated with lipopolysaccharide (LPS) for 24 h were examined by flow cytometry. Immature DCs were divided into 3 groups: negative control group, positive control group (rmIFN-gamma, 1000 U/ml) and rAgB group. Immature DCs of positive control group and rAgB group were induced with 1000 U/ml rmIFN-gamma and 15 microg/ml rAgB, respectively. IDO expression in DCs was examined 24 h after induction using immunohistochemical method and Western blotting.

Results: More than 80% CD11c+ DCs were harvested. The typical DCs were observed under inverted microscope and scanning electronic microscope. The level of CD40, CD80, and IA/IE (MHC II) in mature DCs group was significantly higher than that of immature DCs group (P < 0.05). In MLR, mitomycin-treated DCs can stimulate T lymphocytes proliferation activity. There were significantly differences in IDO expression in the negative control group [(4.544 +/- 1.752)%], positive control group [(20.464 +/- 4.452)%] and rAgB group [(11.148 +/- 1.966)%] (P < 0.05). Western blotting result indicated that the ratio of IDO/GAPDH in rAgB group (0.573 +/- 0.129) was significantly higher than that of negative group (0.229 +/- 0.085) (P < 0.05), and there were no significant difference in the ratio of IDO/GAPDH between IFN-gamma group (0.794 +/- 0.114) and rAgB group (P > 0.05).

Conclusion: rAgB can induce IDO expression in bone marrow-derived dendritic cells in vitro.