CD8

noun

ˌsē-(ˌ)dē-ˈāt 

: 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

Examples of CD8 in a Sentence

Recent Examples on the Web

In a paper published Wednesday in Science Translational Medicine, the team reported that HIV can drive gene expression changes in T cells, turning off their CD4 proteins and turning on a protein called CD8. —Theresa Gaffney, STAT, 4 June 2026

Immigration a top issue in CD8 race The changing politics of immigration have also slipped into one of the state’s most high-profile races this year. —Seth Klamann, Denver Post, 8 Feb. 2026

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

Word History

First Known Use

1984, in the meaning defined above

Medical Definition

CD8

noun

ˌsē-(ˌ)dē-ˈāt 

: 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