虽然人们对 2 型细胞因子白细胞介素 (IL)-4、IL-5 和 IL-13 在体内平衡和疾病中的功能作用了解很多，但我们对 IL-9 的功能仍然知之甚少。然而，过敏性疾病、自身免疫性疾病和癌症中常见的慢性炎症常常伴随着这种难以捉摸的 2 型细胞因子的过量产生。 IL-9 最初被确定为 T 细胞和肥大细胞生长因子，后来被确定为 TH9 细胞的标志性细胞因子，现在我们知道 IL-9 是由多种先天性和适应性免疫细胞产生的。最近的证据表明，IL-9 控制着过敏级联反应、免疫细胞和基质细胞的细胞反应、癌症进展、耐受性和免疫逃逸的各个方面。尽管 IL-9 在粘膜环境（如肺部）中发挥多效细胞因子的作用，但其直接和间接细胞靶标仍未得到很好的表征。在这里，我们讨论 IL-9 的细胞发送者和接收者，重点关注哮喘和癌症。此外，我们回顾了以 IL-9 生物学为中心的当前研究方向和靶向治疗前景。版权所有 © 2024 作者。由爱思唯尔公司出版。保留所有权利。

While much is known about the functional effects of type 2 cytokines interleukin (IL)-4, IL-5 and IL-13 in homeostasis and disease, we still poorly understand the functions of IL-9. Chronic inflammation seen in allergic diseases, autoimmunity and cancer is however frequently accompanied by overproduction of this elusive type 2 cytokine. Initially identified as a T cell and mast cell growth factor, and later as the hallmark cytokine defining TH9 cells, we now know that IL-9 is produced by multiple innate and adaptive immune cells. Recent evidence suggests that IL-9 controls discrete aspects of the allergic cascade, cellular responses of immune and stromal cells, cancer progression, tolerance and immune escape. Despite functioning as a pleiotropic cytokine in mucosal environments, like the lungs, the direct and indirect cellular targets of IL-9 are still not well characterized. Here, we discuss IL-9's cellular senders and receivers, focusing on asthma and cancer. Moreover, we review current research directions and the outlook of targeted therapy centered around the biology of IL-9.Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.