The immune system enables organisms to combat infections and to eliminate endogenous challenges. Immune responses can be evoked through diverse inducible pathways. However, various constitutive mechanisms are also required for immunocompetence. The inducible responses of pattern recognition receptors of the innate immune system and antigen-specific receptors of the adaptive immune system are highly effective, but they also have the potential to cause extensive immunopathology and tissue damage, as seen in many infectious and autoinflammatory diseases. By contrast, constitutive innate immune mechanisms, including restriction factors, basal autophagy and proteasomal degradation, tend to limit immune responses, with loss-of-function mutations in these pathways leading to inflammation. Although they function through a broad and heterogeneous set of mechanisms, the constitutive immune responses all function as early barriers to infection and aim to minimize any disruption of homeostasis. Supported by recent human and mouse data, in this Review we compare and contrast the inducible and constitutive mechanisms of immunosurveillance.

免疫系统使生物体能够抵抗感染并消除内源性挑战。免疫反应可以通过多种诱导途径引起。然而，免疫能力也需要各种组成机制。先天免疫系统的模式识别受体和适应性免疫系统的抗原特异性受体的可诱导反应非常有效，但它们也有可能导致广泛的免疫病理学和组织损伤，如在许多感染性和自身炎症性疾病中所见。相比之下，组成性先天免疫机制，包括限制因子、基础自噬和蛋白酶体降解，往往会限制免疫反应，这些途径中的功能丧失突变会导致炎症。尽管它们通过广泛且异质的机制发挥作用，但组成性免疫反应都作为感染的早期屏障，旨在最大限度地减少体内平衡的任何破坏。在最近的人类和小鼠数据的支持下，在这篇综述中，我们比较和对比了免疫监视的诱导和组成机制。