Partial absence of PD‐1 expression by tumor‐infiltrating EBV‐specific CD8+ T cells in EBV‐driven lymphoepithelioma‐like carcinoma
Lymphoepithelioma‐like carcinoma (LELC) is an uncommon lung cancer, typically observed in young, non‐smoking Asian populations. LELC is associated with Epstein–Barr virus (EBV) infection of lung tumor cells of epithelial origin, suggesting a carcinogenic role of EBV as observed in nasopharyngeal carcinoma (NPC). Here, we studied the antigen specificity and phenotype of EBV‐specific CD8+ T cells in blood and tumor of one LELC patient positive for EBV infection in lung tumor cells.
High-dimensional Characterization of the Systemic Immune Landscape Informs on Synergism between Radiotherapy and Immune Checkpoint Blockade
Improved anti-tumor responses have been observed in patients following combination radiotherapy (RT) and immune checkpoint blockade (ICB). Whether these clinical responses are linked to the host systemic immune system has not been elucidated.
Hepatocellular Carcinoma Cells Upregulate PVRL1, Stabilizing PVR and Inhibiting the Cytotoxic T-cell Response via TIGIT to Mediate Tumor Resistance to PD1 Inhibitors in Mice
Immune checkpoint inhibitors are effective in treatment of some hepatocellular carcinomas (HCCs), but these tumors do not always respond to inhibitors of programmed cell death 1 (PDCD1, also called PD1). We investigated mechanisms of resistance of liver tumors in mice to infiltrating T cells.
Human Tumor-Infiltrating MAIT Cells Display Hallmarks of Bacterial Antigen Recognition in Colorectal Cancer
Growing evidence indicates a role for the gut microbiota in modulating anti-tumor treatment efficacy in human cancer. Here we study mucosa-associated invariant T (MAIT) cells to look for evidence of bacterial antigen recognition in human colon, lung, and kidney carcinomas. Using mass cytometry and single-cell mRNA sequencing, we identify a tumor-infiltrating MAIT cell subset expressing CD4 and Foxp3 and observe high expression of CD39 on MAIT cells from colorectal cancer (CRC) only, which we show in vitro to be expressed specifically after TCR stimulation. We further reveal that these cells are phenotypically and functionally exhausted. Sequencing data show high bacterial infiltration in CRC tumors and highlight an enriched species, Fusobacteria nucleatum, with capability to activate MAIT cells in a TCR-dependent way. Our results provide evidence of a MAIT cell response to microbial antigens in CRC and could pave the way for manipulating MAIT cells or the microbiome for cancer therapy.
Large-Scale HLA Tetramer Tracking of T Cells during Dengue Infection Reveals Broad Acute Activation and Differentiation into Two Memory Cell Fates
T cells play important multifaceted roles during dengue infection, and understanding their responses is important for defining correlates of protective immunity and identifying effective vaccine antigens. Using mass cytometry and a highly multiplexed peptide-HLA (human leukocyte antigen) tetramer staining strategy, we probed T cells from dengue patients-a total of 430 dengue and control candidate epitopes-together with key markers of activation, trafficking, and differentiation. During acute disease, dengue-specific CD8+ T cells expressed a distinct profile of activation and trafficking receptors that distinguished them from non-dengue-specific T cells. During convalescence, dengue-specific T cells differentiated into two major cell fates, CD57+ CD127–-resembling terminally differentiated senescent memory cells and CD127+ CD57–-resembling proliferation-capable memory cells. Validation in an independent cohort showed that these subsets remained at elevated frequencies up to one year after infection. These analyses aid our understanding of the generation of T cell memory in dengue infection or vaccination.