CD4 and CD8 T cells are key players in the immune response against both pathogenic infections and cancer. CD4 T cells provide help to CD8 T cells via multiple mechanisms, including licensing dendritic cells (DCs), co-stimulation, and cytokine production. During acute infection and vaccination, CD4 T cell help is important for the development of CD8 T cell memory. However, during chronic viral infection and cancer, CD4 helper T cells are critical for the sustained effector CD8 T cell response, through a variety of mechanisms. In this review, we focus on T cell responses in conditions of chronic Ag stimulation, such as chronic viral infection and cancer. In particular, we address the significant role of CD4 T cell help in promoting effector CD8 T cell responses, emerging techniques that can be utilized to further our understanding of how these interactions may take place in the context of tertiary lymphoid structures, and how this key information can be harnessed for therapeutic utility against cancer.

中文翻译：

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CD4 T 细胞在慢性感染和癌症期间帮助 CD8 T 细胞分化和功能的作用。

CD4 和 CD8 T 细胞是针对病原体感染和癌症的免疫反应的关键参与者。CD4 T 细胞通过多种机制为 CD8 T 细胞提供帮助，包括许可树突状细胞 (DC)、共刺激和细胞因子产生。在急性感染和疫苗接种期间，CD4 T 细胞的帮助对于 CD8 T 细胞记忆的发展非常重要。然而，在慢性病毒感染和癌症期间，CD4 辅助 T 细胞通过多种机制对于持续效应 CD8 T 细胞反应至关重要。在这篇综述中，我们重点关注慢性 Ag 刺激条件下的 T 细胞反应，例如慢性病毒感染和癌症。特别是，我们讨论了 CD4 T 细胞在促进效应 CD8 T 细胞反应中的重要作用，新兴技术可用于进一步了解这些相互作用如何在三级淋巴结构中发生，以及这一关键作用如何发挥作用。信息可用于治疗癌症。