{"entity":{"id":"t-cell","kind":"term","name":"T cell","aka":["T cells","T-cell","T-cells","T lymphocyte","T lymphocytes","cytotoxic T cell","cytotoxic T cells","CD8 T cell","CD8 T cells","CD8+ T cell","CD8+ T cells","CD8+","CD4+","helper T cell","helper T cells","regulatory T cell","regulatory T cells","Treg","Tregs","killer T cell","killer T cells","T-cell exhaustion","exhausted T cells"],"tldr":"The immune system's trained assassins. Each T cell recognises one specific target displayed on a cell's surface and, if the cell is infected or cancerous, kills it. Most immunotherapy is about unleashing them.","summary":"T cells mature in the thymus and use a receptor (TCR) to inspect peptide fragments held in HLA molecules on other cells; cytotoxic CD8 T cells kill, CD4 helper cells coordinate, and regulatory T cells damp the response down. Tumours evade them by switching on checkpoints such as PD-L1, which exhausts the T cells that reach them, and by losing HLA so there is nothing to inspect. Checkpoint inhibitors reinvigorate exhausted T cells; CAR-T and TCR-T engineer a patient's own T cells with a new targeting receptor; bispecific T-cell engagers grab a T cell with one arm and a tumour cell with the other; and tumour-infiltrating lymphocyte (TIL) therapy expands the T cells already inside a tumour.","asOf":"2026-09-09","wikipedia":"https://en.wikipedia.org/wiki/T_cell","links":[{"label":"Wikipedia","url":"https://en.wikipedia.org/wiki/T_cell"}],"tags":[],"related":["immune-system","b-cell","nk-cell","antigen","epitope","immune-checkpoint","tils","neoantigen","cytokine","crs"],"cancers":[],"sections":[],"technologies":["checkpoint-inhibitor","car-t","tcr-t","t-cell-engager","til-therapy"],"targets":["pd1","pdl1","ctla4","cd3","lag3"],"drugs":[],"companies":[],"institutions":[],"pathways":["pd1-checkpoint"],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"category":"Biology basics"},"route":"/terms/t-cell/","neighbours":{"term":[{"id":"antigen","kind":"term","name":"Antigen","route":"/terms/antigen/"},{"id":"b-cell","kind":"term","name":"B cell","route":"/terms/b-cell/"},{"id":"cytokine","kind":"term","name":"Cytokine","route":"/terms/cytokine/"},{"id":"crs","kind":"term","name":"Cytokine release syndrome (CRS)","route":"/terms/crs/"},{"id":"epitope","kind":"term","name":"Epitope","route":"/terms/epitope/"},{"id":"immune-checkpoint","kind":"term","name":"Immune checkpoint","route":"/terms/immune-checkpoint/"},{"id":"immune-system","kind":"term","name":"Immune system","route":"/terms/immune-system/"},{"id":"immunotherapy-term","kind":"term","name":"Immunotherapy","route":"/terms/immunotherapy-term/"},{"id":"lymph-node","kind":"term","name":"Lymph node","route":"/terms/lymph-node/"},{"id":"lymphoma-type","kind":"term","name":"Lymphoma (tissue type)","route":"/terms/lymphoma-type/"},{"id":"neoantigen","kind":"term","name":"Neoantigen","route":"/terms/neoantigen/"},{"id":"nk-cell","kind":"term","name":"NK cell","route":"/terms/nk-cell/"},{"id":"tils","kind":"term","name":"Tumour-infiltrating lymphocytes (TILs)","route":"/terms/tils/"}],"technology":[{"id":"car-t","kind":"technology","name":"CAR-T cell therapy","route":"/technologies/car-t/"},{"id":"checkpoint-inhibitor","kind":"technology","name":"Immune checkpoint inhibitors","route":"/technologies/checkpoint-inhibitor/"},{"id":"t-cell-engager","kind":"technology","name":"T-cell engagers (bispecific)","route":"/technologies/t-cell-engager/"},{"id":"tcr-t","kind":"technology","name":"TCR-T cell therapy","route":"/technologies/tcr-t/"},{"id":"til-therapy","kind":"technology","name":"TIL therapy","route":"/technologies/til-therapy/"}],"target":[{"id":"cd3","kind":"target","name":"CD3","route":"/targets/cd3/"},{"id":"ctla4","kind":"target","name":"CTLA-4","route":"/targets/ctla4/"},{"id":"lag3","kind":"target","name":"LAG-3","route":"/targets/lag3/"},{"id":"pd1","kind":"target","name":"PD-1","route":"/targets/pd1/"},{"id":"pdl1","kind":"target","name":"PD-L1","route":"/targets/pdl1/"}],"pathway":[{"id":"pd1-checkpoint","kind":"pathway","name":"PD-1 / PD-L1 immune checkpoint & T-cell activation","route":"/pathways/pd1-checkpoint/"}],"person":[{"id":"robert-negrin","kind":"person","name":"Robert Negrin","route":"/people/robert-negrin/"}]}}