Project description:The Germinal center is a dynamic microenvironment wherein B cells expressing high affinity antibody variants produced by hypermutation are selected for clonal expansion by limiting numbers of T follicular helper cells. Although a great deal is known about the mechanisms that control B cell selection in the germinal center, far less is understood about the clonal behavior of the T follicular helper cells that regulate this process. Here we report on the dynamic behavior of clones of T follicular helper cells during the germinal center reaction. We find that like germinal center B cells, T follicular helper cells undergo antigen dependent selection during the germinal center reaction resulting in differential proliferative expansion and contraction. Increasing the amount of antigen presented in the germinal center leads to increased T follicular cell division. Competition between T follicular helper cell clones is mediated by T cell receptor affinity for peptide-MHC ligand. Higher affinity T cells expanding preferentially in the germinal center show increased expression of genes downstream of the T cell receptor, genes required for metabolic reprogramming, cell division and cytokine production. These dynamic changes lead to dramatic remodeling of the functional T follicular cell repertoire during the germinal center reaction.
Project description:A prospective study for investigating the T-cell receptor (TCR) repertoire in T-cell mediated rejection (TCMR) after kidney transplantation. The pre-formed donor-reactive TCR repertoire was tracked in blood and tissue of patients after kidney transplantation and characteristics of TCR repertoires from patients experiencing a rejection were compared to patients with no histopathological signs of rejection.
Project description:Emerging evidence suggests that an increased density of pre-treatment CD8+ tumor-infiltrating lymphocytes (TILs) is associated with good response to chemoradiotherapy (CRT) in patients with locally advanced rectal cancer. However, the significance of T-cell complexity in the clinical setting remains unknown. High-throughput T-cell receptor (TCR) β sequencing was applied to quantify the TCR repertoire of pre-treatment biopsies from 67 patients with advanced rectal cancer receiving preoperative CRT. Changes in TCR repertoire before and after CRT were also analysed in 23 patients.
Project description:CD4 T cell help is critical for both the generation and maintenance of germinal centers, and T follicular helper (TFH) cells are the CD4 T cell subset required for this process. SAP (SH2D1A) expression in CD4 T cells is essential for germinal center development. However, SAP-deficient mice have only a moderate defect in TFH differentiation as defined by common TFH surface markers. CXCR5+ TFH cells are found within the germinal center as well as along the boundary regions of T/B cell zones. Here we show that germinal center associated T cells (GC TFH) can be identified by their co-expression of CXCR5 and the GL7 epitope, allowing for phenotypic and functional analysis of TFH and GC TFH populations. Here we show GC TFH are a functionally discrete subset of further polarized TFH cells, with enhanced B cell help capacity and a specialized ability to produce IL-4 in a TH2-independent manner. Strikingly, SAP-deficient mice have an absence of the GC TFH subset and SAP- TFH are defective in IL-4 and IL-21 production. We further demonstrate that SLAM (Slamf1, CD150), a surface receptor that utilizes SAP signaling, is specifically required for IL-4 production by GC TFH. GC TFH cells require IL-4 and IL-21 production for optimal help to B cells. These data illustrate complexities of SAP-dependent SLAM family receptor signaling, revealing a prominent role for SLAM receptor ligation in IL-4 production by germinal center CD4 T cells but not in TFH and GC TFH differentiation. This SuperSeries is composed of the following subset Series: GSE21379: Expression Data from WT and Sh2d1a-/- in vivo follicular helper CD4 T cells (TFH) versus non follicular helper CD4 T cells (non-TFH) GSE21380: Expression Data from in vivo Tfh vs GC Tfh vs non-Tfh Refer to individual Series