Microarray expression data from monocytes, Mo-DCs and CD24 DCs

Cross-presentation of cell-associated antigens is carried out by classical DCs (cDCs) and monocyte-derived DCs (Mo-DCs), but whether a similar or distinct program exists for this process is unknown. In examining this issue, we discovered that only Ly-6ChiTremL4- monocytes, but not Ly-6ChiTremL4+ monocytes, can differentiate into Zbtb46+ Mo-DCs in response to GM-CSF and IL-4. However, Ly-6ChiTremL4+ monocytes were committed to Nur77-dependent development of Ly-6CloTremL4+ monocytes. Further, differentiation of monocytes with GM-CSF required addition of IL-4 to generate Zbtb46+ Mo-DCs that cross-presented as efficiently as CD24+ cDCs, which was accompanied by increased Batf3 and Irf4 expression. Unlike cDCs, Mo-DCs required only IRF4, and not Batf3, for cross-presentation. Further, Irf4-/- monocytes failed to develop into Zbtb46+ Mo-DCs, and instead developed into macrophages. Thus, cDCs and Mo-DCs use distinct transcriptional programs for cross-presentation that may drive different antigen-processing pathways. These differences may influence development of therapeutic DC vaccines based on Mo-DCs. Mo-DCs from WT and IRF4KO mice, BM Ly-6ChiTremL4- and Ly-6CloTremL4+ monocytes, and WT CD24+ DCs were sorted to >95% purity on FACSAria Fusion细胞相关抗原的交叉呈递（cross-presentation）由经典树突状细胞（classical DCs, cDCs）与单核细胞衍生树突状细胞（monocyte-derived DCs, Mo-DCs）介导，但目前尚不明确该过程是否存在相似或差异化的调控程序。针对该问题开展研究时，我们发现仅Ly-6C高表达、TremL4阴性（Ly-6ChiTremL4-）的单核细胞，在粒细胞-巨噬细胞集落刺激因子（GM-CSF）与白细胞介素4（IL-4）诱导下，可分化为Zbtb46阳性的单核细胞衍生树突状细胞；而Ly-6C高表达、TremL4阳性（Ly-6ChiTremL4+）的单核细胞则定向走向依赖Nur77的Ly-6C低表达、TremL4阳性（Ly-6CloTremL4+）单核细胞发育通路。进一步研究显示，利用GM-CSF诱导单核细胞分化时，需额外添加IL-4才能生成Zbtb46阳性的单核细胞衍生树突状细胞，其交叉呈递效率可与CD24阳性经典树突状细胞（CD24+ cDCs）相当，且该过程伴随Batf3与Irf4表达水平上调。与经典树突状细胞不同，单核细胞衍生树突状细胞的交叉呈递仅依赖IRF4，而非Batf3。此外，Irf4基因敲除（Irf4-/-）的单核细胞无法分化为Zbtb46阳性的单核细胞衍生树突状细胞，反而会分化为巨噬细胞。综上，经典树突状细胞与单核细胞衍生树突状细胞采用截然不同的转录调控程序完成交叉呈递，这可能对应不同的抗原加工通路。上述差异或可影响基于单核细胞衍生树突状细胞的治疗性树突状疫苗研发。本研究通过FACSAria Fusion流式细胞分选仪，将野生型（WT）与Irf4基因敲除（IRF4KO）小鼠来源的单核细胞衍生树突状细胞、骨髓来源的Ly-6ChiTremL4-及Ly-6CloTremL4+单核细胞，以及野生型CD24+经典树突状细胞分选至纯度>95%。