Glucocorticoids (GCs) are small lipid hormones produced by the adrenals that maintain organismal homeostasis. Circadian and stress-induced changes in systemic GC levels regulate metabolism, cardiovascular and neural function, reproduction and immune activity. Our understanding of GC effects on immunity comes largely from administration of exogenous GCs to treat immune or inflammatory disorders. However, it is increasingly clear that endogenous GCs both promote and suppress T cell immunity. Examples include selecting an appropriate repertoire of T cell receptor (TCR) self-affinities in the thymus, regulating T cell trafficking between anatomical compartments, suppressing type 1 T helper (T_H1) cell responses while permitting T_H2 cell and, especially, IL-17-producing T helper cell responses, and promoting memory T cell differentiation and maintenance. Furthermore, in addition to functioning at a distance, extra-adrenal (local) production allows GCs to act as paracrine signals, specifically targeting activated T cells in various contexts in the thymus, mucosa and tumours. These pleiotropic effects on different T cell populations during development and immune responses provide a nuanced understanding of how GCs shape immunity.

糖皮质激素 (GC) 是由肾上腺产生的小脂质激素，可维持机体稳态。昼夜节律和压力引起的全身 GC 水平变化调节新陈代谢、心血管和神经功能、繁殖和免疫活动。我们对 GC 对免疫影响的理解主要来自于使用外源性 GC 来治疗免疫或炎症性疾病。然而，越来越清楚的是，内源性 GC 既能促进也能抑制 T 细胞免疫。例子包括在胸腺中选择合适的 T 细胞受体 (TCR) 自身亲和力库、调节解剖区室之间的 T 细胞运输、抑制 1 型 T 辅助 (T _H 1) 细胞反应，同时允许 T _H2 细胞，尤其是产生 IL-17 的 T 辅助细胞反应，并促进记忆性 T 细胞分化和维持。此外，除了在远处发挥作用外，肾上腺外（局部）的产生还允许 GC 充当旁分泌信号，专门针对胸腺、粘膜和肿瘤中各种环境中的活化 T 细胞。这些在发育和免疫反应过程中对不同 T 细胞群的多效作用提供了对 GC 如何塑造免疫的细致入微的理解。