Baumjohann Dirk, Ansel K Mark
Department of Microbiology & Immunology, Sandler Asthma Basic Research Center, University of California San Francisco, San Francisco, CA, 94143, USA,
Methods Mol Biol. 2015;1291:27-38. doi: 10.1007/978-1-4939-2498-1_3.
T follicular helper (Tfh) cells provide essential help to B cells for the generation of high-affinity antibodies. These mechanisms provide the basis for the success of modern vaccines, but dysregulated Tfh cell responses are also linked to autoimmune diseases. In addition to their established role in driving humoral immunity, Tfh cells are gaining attention for their role in other processes of the adaptive immune system. For example, Tfh cells may serve as transitional differentiation intermediates during effector and memory T-helper cell differentiation and as a reservoir of HIV-infected cells. While B cells are required for the full maturation and maintenance of Tfh cell responses, they are dispensable for the initial induction of the Tfh cell phenotype, which occurs at the priming stage through interaction with dendritic cells. Nevertheless, the precise mechanisms of these early events during Tfh cell differentiation remain relatively unknown. Here, we describe a method for tracking early Tfh cell differentiation by following cell division kinetics and phenotypic changes of recently activated antigen-specific CD4(+) T cells in vivo. As an example, we use this method to visualize the requirements for T cell-expressed CD28 for the differentiation of CXCR5(+)Bcl6(+) Tfh cells.
滤泡辅助性T（Tfh）细胞为B细胞产生高亲和力抗体提供关键帮助。这些机制为现代疫苗的成功奠定了基础，但Tfh细胞反应失调也与自身免疫性疾病有关。除了在驱动体液免疫中已确立的作用外，Tfh细胞在适应性免疫系统的其他过程中的作用也日益受到关注。例如，Tfh细胞可能在效应性和记忆性辅助性T细胞分化过程中充当过渡性分化中间体，并作为HIV感染细胞的储存库。虽然B细胞对于Tfh细胞反应的完全成熟和维持是必需的，但对于Tfh细胞表型的初始诱导却是可有可无的，Tfh细胞表型的初始诱导在启动阶段通过与树突状细胞的相互作用而发生。然而，Tfh细胞分化过程中这些早期事件的确切机制仍然相对不明。在此，我们描述了一种通过追踪体内最近激活的抗原特异性CD4(+) T细胞的细胞分裂动力学和表型变化来跟踪早期Tfh细胞分化的方法。例如，我们使用这种方法来可视化T细胞表达的CD28对CXCR5(+)Bcl6(+) Tfh细胞分化的需求。
