{"entity":{"id":"cd8","kind":"target","name":"CD8","aka":["CD8a","CD8 alpha","T8"],"tldr":"CD8 marks the T cells that kill: the ones that recognise a cancer cell and destroy it. How many CD8 cells sit inside a tumour, and where, is one of the few immune measurements that predicts how a cancer will behave.","summary":"CD8 is the co-receptor that binds MHC class I and defines cytotoxic T cells, the cells that kill a target directly. It is the marker behind the phrase 'tumour-infiltrating lymphocytes' and behind the distinction between a hot and a cold tumour. Its density is prognostic rather than merely descriptive: the international consensus Immunoscore study quantified CD3 and CD8 densities in the tumour centre and the invasive margin in 1,885 stage I/II colon cancers across Canada, the United States, Europe and Asia, and a high Immunoscore carried the lowest risk of recurrence in both cohorts. CD8 is a two-chain receptor; CD8A is the alpha chain given here and CD8B (HGNC:1707) the beta.","asOf":"2026-10-16","wikipedia":"https://en.wikipedia.org/wiki/CD8","links":[{"label":"HGNC:1706","url":"https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:1706"},{"label":"Consensus Immunoscore in stage I/II colon cancer (Cancers 2023)","url":"https://doi.org/10.3390/cancers15020418"}],"tags":["immune-marker"],"related":["cd4","pd1"],"cancers":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":["t-cell","cold-vs-hot","t-cell-exhaustion-term"],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"CD8A","role":[],"sources":[],"specificitySources":[],"biology":"Co-receptor on cytotoxic T cells; binds MHC class I and marks the killing lineage. The beta chain is CD8B (HGNC:1707).","whereFound":["Cytotoxic T cells","Some natural killer cells"],"targetClass":"surface-antigen","prevalence":[]},"route":"/targets/cd8/","neighbours":{"target":[{"id":"cd4","kind":"target","name":"CD4","route":"/targets/cd4/"},{"id":"cd57","kind":"target","name":"CD57","route":"/targets/cd57/"},{"id":"cxcr3","kind":"target","name":"CXCR3","route":"/targets/cxcr3/"},{"id":"pd1","kind":"target","name":"PD-1","route":"/targets/pd1/"}],"term":[{"id":"cold-vs-hot","kind":"term","name":"Hot vs cold tumours","route":"/terms/cold-vs-hot/"},{"id":"t-cell","kind":"term","name":"T cell","route":"/terms/t-cell/"},{"id":"t-cell-exhaustion-term","kind":"term","name":"T-cell exhaustion and CAR-T persistence","route":"/terms/t-cell-exhaustion-term/"}]}}