[Bioimmunological characteristics of mature or immature murine dendritic cells].

Objective: To explore the biological characteristics of immature and mature murine bone marrow-derived dendritic cells (DCs).

Methods: The murine bone marrow cells were cultured and induced in vitro into immature DCs (imDCs). Then ImDCs were incubated with TNF (tumor necrosis factor)-α to obtain mature DCs (mDCs). The DCs were purified by murine CD11c microbeads. The morphologies of DCs were observed by electron microscopy (EM). Such surface markers as MHC-II, CD80 and CD86 were tested by flow cytometry (FCM). The proliferation capacity of allogeneic T cells stimulated by DCs was examined by Cell Counting Kit-8 (CCK-8) in mixed lymphocyte reaction (MLR). The expressions of cell factors in mRNA of DCs were tested by real-time polymerase chain reaction (QPCR). The cytokines in supernatant were measured by ELISA (enzyme-linked immunosorbent assay).

Results: As compared with mDCs, fewer, shorter spines and more phagocytic vesicles and lysosome were observed in imDCs under EM. The expressions of cell surface molecules in imDCs were significantly lower than those of mDC by FCM, [MHC-II (27.2%) vs (97.7%); CD80 (27.6%) vs (97.2%); CD86 (29.5%) vs (96.4%)]. In MLR, the capacity of same-reaction ratio imDCs group for stimulating the proliferation of T-cells was remarkably lower than that of mDCs group,[1:5 (1.63 ± 0.04) vs (2.21 ± 0.09); 1:10 (1.50 ± 0.08) vs (1.92 ± 0.02); 1:20 (1.28 ± 0.07) vs (1.64 ± 0.01); 1:40 (1.19 ± 0.04) vs (1.45 ± 0.06), P < 0.01]. In imDCs, the relative mRNA expressions of IL12p35 (0.66 ± 0.13), IL12p40 (0.57 ± 0.10) and IFN-γ (0.74 ± 0.08) were lower than those of mDCs (1.00 ± 0.00), (P < 0.05), but the expression of TGF-β (1.35 ± 0.09) was higher than that of mDCs by QPCR (1.00 ± 0.00), (P < 0.05). The expressions of IL12p70 and IFN-γ in supernatants from imDCs were lower than those of mDCs [IL12p70: (6 ± 4) vs (120 ± 22); IFN-γ: (56 ± 15) vs (90 ± 15), P < 0.05] while the expression of TGF (transforming growth factor)-β was higher than that of mDCs by ELISA [TGF-β: (176 ± 23) vs (55 ± 18), P < 0.05].

Conclusion: ImDCs can induce anergic T cells and immune tolerance through a down-regulation of co-stimulatory molecules, MHC-II and Th1 cytokines and an up-regulation of Th2 cytokine (TGF-β). And MDCs may activate naive T cells and stimulate immune responses by an up-regulation of co-stimulatory molecules, MHC-II and Th1 cytokines.