: a large glycoprotein that is found associated with a T cell receptor especially on the surface of helper T cells and that binds to a major histocompatibility complex molecule on the surface of an antigen-presenting cell to facilitate antigen recognition and T cell activation
often used before another noun
the CD4 geneCD4 T cells [=T cells bearing CD4 on their surface]

Note: CD4 is a receptor for HIV, and cells of the immune system bearing CD4 on their surface are preferentially infected with the virus and become progressively depleted.

compare CD8

Word History

Etymology

cluster of differentiation

First Known Use

1984, in the meaning defined above

Time Traveler
The first known use of CD4 was in 1984

Dictionary Entries Near CD4

Cite this Entry

“CD4.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/CD4. Accessed 6 Feb. 2023.

Medical Definition

: a large glycoprotein that is found associated with a T cell receptor especially on the surface of helper T cells and that binds to a major histocompatibility complex molecule on the surface of an antigen-presenting cell to facilitate antigen recognition and T cell activation
often used before another noun
the CD4 geneCD4 T cells [=T cells bearing CD4 on their surface]

Note: CD4 is a receptor for HIV and cells of the immune system bearing CD4 on their surface are preferentially infected with the virus and become progressively depleted.

compare cd8
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