CD4
noun
: 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 gene
CD4 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 CD8Examples of CD4 in a Sentence
Recent Examples on the Web
However, if the CD4 count drops below 50, the chances of immune reconstitution are reduced.
—
Anju Goel, Verywell Health, 22 Mar. 2025
Without medication, people with HIV will experience a rebound in their viral loads, while also experiencing a lower number of disease-fighting cells, known as CD4 cells.
—Mathew Rodriguez, Them, 28 Jan. 2025
Rao and his colleagues identified CD4 T cells — or pathogenic T cells — as the ones causing an imbalance of B cells.
—Joshua Rapp Learn, Discover Magazine, 10 Sep. 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
The enveloped and the lentiviral vector displayed CD3, CD4 and CD28-targeting antibody fragments on their surface to target T cells.
—William A. Haseltine, Forbes, 14 Feb. 2024
There’s no shortage of follow-up questions to investigate: How exactly are all these immune cells getting activated by CD4+?
—Isabella Cueto, STAT, 14 July 2023
In the cases where people had few CD4 cells, mpox’s normally small skin lesions grew into large necrotizing patches and their infection sometimes spread to the lungs or caused severe secondary infections with bacteria.
—Bykai Kupferschmidt, science.org, 21 Feb. 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
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Anju Goel, Verywell Health, 22 Mar. 2025
Without medication, people with HIV will experience a rebound in their viral loads, while also experiencing a lower number of disease-fighting cells, known as CD4 cells.
—Mathew Rodriguez, Them, 28 Jan. 2025
Rao and his colleagues identified CD4 T cells — or pathogenic T cells — as the ones causing an imbalance of B cells.
—Joshua Rapp Learn, Discover Magazine, 10 Sep. 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
The enveloped and the lentiviral vector displayed CD3, CD4 and CD28-targeting antibody fragments on their surface to target T cells.
—William A. Haseltine, Forbes, 14 Feb. 2024
There’s no shortage of follow-up questions to investigate: How exactly are all these immune cells getting activated by CD4+?
—Isabella Cueto, STAT, 14 July 2023
In the cases where people had few CD4 cells, mpox’s normally small skin lesions grew into large necrotizing patches and their infection sometimes spread to the lungs or caused severe secondary infections with bacteria.
—Bykai Kupferschmidt, science.org, 21 Feb. 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
Cite this Entry
“CD4.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/CD4. Accessed 30 Jul. 2025.
Copy CitationMedical Definition
CD4
noun
: 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 gene
CD4 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.
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