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

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

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