PNAS：树突细胞参与调节过敏反应

深入认识感染可能有助于科学家们理解过敏症和开发新的治疗方法。在一项新研究中，英国爱丁堡大学研究人员对免疫系统的研究揭示出一种参与身体对诸如花粉或宠物毛发之类的过敏原产生的免疫反应的细胞所发挥的作用。这种细胞被称作树突细胞，已知它起着协调身体对感染产生免疫反应的作用。它是通过让免疫系统激活抵抗感染的白细胞来发挥功能的。

研究人员证实当身体免疫反应过于活跃且可能造成伤害时，树突细胞也能够在抑制这种免疫反应中发挥着作用。事实上，它们能够作为免疫系统的调节者发挥作用，有助于抑制免疫系统。

当免疫系统对过敏原作出过度反应时，过敏反应就会产生。研究人员说，他们的发现让人们对参与过敏反应的免疫反应类型产生新的认识。

研究人员通过在小鼠体内和实验室测试中研究免疫反应而证实了上述发现。他们说，它有助于解释身体如何控制抵御感染的战斗和如何寻求恢复稳定，而且它可能让人们能够控制在过敏反应中发现的炎症。

本文编译自Findings could keep allergies in check

doi: 10.1073/pnas.1121231109
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Alternatively activated dendritic cells regulate CD4+ T-cell polarization in vitro and in vivo

Peter C. Cooka,1, Lucy H. Jonesa,1, Stephen J. Jenkinsa, Thomas A. Wynnb, Judith E. Allena, and Andrew S. MacDonald

Interleukin-4 is a cytokine widely known for its role in CD4+ T cell polarization and its ability to alternatively activate macrophage populations. In contrast, the impact of IL-4 on the activation and function of dendritic cells (DCs) is poorly understood. We report here that DCs respond to IL-4 both in vitro and in vivo by expression of multiple alternative activation markers with a different expression pattern to that of macrophages. We further demonstrate a central role for DC IL-4Rα expression in the optimal induction of IFNγ responses in vivo in both Th1 and Th2 settings, through a feedback loop in which IL-4 promotes DC secretion of IL-12. Finally, we reveal a central role for RELMα during T-cell priming, establishing that its expression by DCs is critical for optimal IL-10 and IL-13 promotion in vitro and in vivo. Together, these data highlight the significant impact that IL-4 and RELMα can have on DC activation and function in the context of either bacterial or helminth pathogens.