Functional analyses of dendritic subsets in immune regulation

在这个项目中，我们从细胞因子产生、T细胞活化和调节性T细胞扩增的角度研究了内噬常规树突状细胞（DCs）和I型干扰素产生浆细胞样preDCs （P-preDCs）在免疫调节方面的功能差异。得到了以下结果：1)Ly49Q是Ly49家族的成员，在Gr-1^+细胞上表达，而在NK和NKT细胞上不表达。常规dc表达Ly49Q为阴性，而骨髓源性dc表达水平低，受IFN上调。另一方面，Ly49Q在外周血淋巴组织CD11c^+B220^+Gr-1^+ p - predc上表达。然而，p - predc在骨髓中的表达水平是可变的。这与P-preDCs分化阶段不同有关，因为Ly49Q在培养时自发表达，Ly49Q^+P-preDCs通过CpG-ODN产生大量的IFN-α/β、IL-6和IL-12。2)已知CD25^+CD4^+调节性或抑制性t细胞（Tregs）维持免疫自身耐受性，防止自身免疫。以前我们已经证明，当apc是抗原负载的成熟树突状细胞（dc）时，treg增殖并保留其抗原依赖的抑制功能。使用同种异体多克隆treg， dc被证明可以有效地维持treg中Foxp3的表达，并且在IL-2存在下可以有效地扩增异体抗原特异性treg。此外，扩增的Tregs能有效抑制CD25- CD4- T细胞诱导的GvHD。3)我们培育了在Langerin位点有一个灵长类DTR靶向插入的小鼠。注射DT后24 h内，LCs在Langerin-DTR成年小鼠体内有效选择性消融。在稳定状态下，表皮LC室的重建至少需要4周。lc -缺失小鼠的功能分析显示，真皮dc能够介导皮肤CHS反应。

In this project, we examined functional differences of endocytoic conventional dendritic cells (DCs) with type I interferon-producing plasmacyotoid preDCs (P-preDCs) in immune regulations in terms of cytokine production, T cell activation, and expansion of regulatory T cells. The following results were obtained.1)Ly49Q is a member of the Ly49 family that is expressed on Gr-1^+ cells, but not on NK and NKT cells. Conventional DCs were found to be negative for Ly49Q, while bone marrow-derived DCs expressed at low level and upregulated by IFN. On the other hand, Ly49Q was expressed on CD11c^+B220^+Gr-1^+P-preDCs in peripheral lymphoid tissues. However, the expression level on P-preDCs were variable in bone marrow. This was ascribed to the difference in differentiation stage of P-preDCs, since Ly49Q was expressed spontaneously upon culture and Ly49Q^+P-preDCs produced larger amounts of IFN-α/β,IL-6 and IL-12 by CpG-ODN.2)CD25^+CD4^+ regulatory or suppressor Tcells (Tregs) is known to maintain immunological self-tolerance, preventing autoimmunity. Previously we have shown that Tregs proliferate and retain their antigen-dependent suppressive functions when the APCs are antigen-loaded mature dendritic cells (DCs). Using allogeneic polyclonal Tregs, DCs were demonstrated to effectively sustain expression of Foxp3 in Tregs and to be potent for the expansion of alloantigen-specific Tregs in the presence of IL-2. Moreover, those expanded Tregs were efficient to suppressed GvHD induced by CD25- CD4- T cells.3)We generated mice that harbor a targeted insertion of a primate DTR in the Langerin locus. LCs were effectively and selectively ablated in adult Langerin-DTR mice within 24 h after injection of DT. Reconstitution of the epidermal LC compartment in the steady state took at least 4 wk. Functional analysis of LC-depleted mice revealed that dermal DCs were able to mediate a cutaneous CHS response.