CD8
noun
: a glycoprotein that is found associated with a T cell receptor especially on the surface of a cytotoxic T cell and that binds to a major histocompatibility complex molecule on the surface of an antigen-presenting cell to facilitate antigen recognition and cytotoxic T cell activation
—often used before another noun
CD8 surface markers
CD8 cells [=cells bearing CD8 on their surface]
… the CD8 molecule is closely associated with MHC class I molecules on antigen-presenting cells.—
Scientific American Medicine
compare CD4
Scientific American MedicineExamples of CD8 in a Sentence
Recent Examples on the Web
Study 1 The researchers looked closely at key cancer-killing immune cells called CD8+ T cells, also known as cytotoxic T cells.
—New Atlas, 20 Sep. 2025
Go deeper: Hamadeh wins CD8 Republican primary Slugfest between Hamadeh and Masters dominates CD8 Republican primary
9th Congressional District: Paul Gosar (R)
Longtime Rep. Paul Gosar is running unopposed in his district, which encompasses parts of the West Valley and northwestern Arizona.
—Jessica Boehm, Axios, 9 Oct. 2024
Schoenberger said the next path of exploration is to explore ways that antigens that activate CD4 and CD8 T-cells could be linked.
—Paul Sisson, San Diego Union-Tribune, 6 Mar. 2024
In the last few years, some in the field have thought tumor-fighting CD8+ T cells come in to suppress the disease-causing immune response of CD4+ cells.
—Isabella Cueto, STAT, 14 July 2023
When the adaptive response starts taking effect, CD4+ and CD8+ T-cells are released which play an important role in coordinating a sustained immune response and killing off infected cells.
—William A. Haseltine, Forbes, 13 Feb. 2023
The scientists looked for antibodies, memory B cells, CD8+ T cells, and CD4+ T cells, all fighting SARS-CoV-2.
—Adam Rogers, Wired, 5 Mar. 2021
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New Atlas, 20 Sep. 2025
Go deeper: Hamadeh wins CD8 Republican primary Slugfest between Hamadeh and Masters dominates CD8 Republican primary
9th Congressional District: Paul Gosar (R)
Longtime Rep. Paul Gosar is running unopposed in his district, which encompasses parts of the West Valley and northwestern Arizona.
—Jessica Boehm, Axios, 9 Oct. 2024
Schoenberger said the next path of exploration is to explore ways that antigens that activate CD4 and CD8 T-cells could be linked.
—Paul Sisson, San Diego Union-Tribune, 6 Mar. 2024
In the last few years, some in the field have thought tumor-fighting CD8+ T cells come in to suppress the disease-causing immune response of CD4+ cells.
—Isabella Cueto, STAT, 14 July 2023
When the adaptive response starts taking effect, CD4+ and CD8+ T-cells are released which play an important role in coordinating a sustained immune response and killing off infected cells.
—William A. Haseltine, Forbes, 13 Feb. 2023
The scientists looked for antibodies, memory B cells, CD8+ T cells, and CD4+ T cells, all fighting SARS-CoV-2.
—Adam Rogers, Wired, 5 Mar. 2021
Cite this Entry
“CD8.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/CD8. Accessed 21 Oct. 2025.
Copy CitationMedical Definition
CD8
noun
: a glycoprotein that is found associated with a T cell receptor especially on the surface of a cytotoxic T cell and that binds to a major histocompatibility complex molecule on the surface of an antigen-presenting cell to facilitate antigen recognition and cytotoxic T cell activation
—often used before another noun
CD8 surface markers
CD8 cells [=cells bearing CD8 on their surface]
… the CD8 molecule is closely associated with MHC class I molecules on antigen-presenting cells.—Scientific American Medicine
compare cd4
Scientific American MedicineLove words? Need even more definitions?
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