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• T cell
  T cell

  noun

  any of several closely related lymphocytes, developed in the thymus, that circulate in the blood and lymph and orchestrate the immune system's response to infected or malignant cells, either by lymphokine secretions or by direct contact: helper T cells recognize foreign antigen on the surfaces of other cells, then they stimulate B cells to produce antibody and signal killer T cells to destroy the antigen-displaying cells; subsequently suppressor T cells return the immune system to normal by inactivating the B cells and killer T cells.
• T-cell
  T-cell

  noun

  another name for T-lymphocyte

T cell

American  

noun

Immunology.

1. any of several closely related lymphocytes, developed in the thymus, that circulate in the blood and lymph and orchestrate the immune system's response to infected or malignant cells, either by lymphokine secretions or by direct contact: helper T cells recognize foreign antigen on the surfaces of other cells, then they stimulate B cells to produce antibody and signal killer T cells to destroy the antigen-displaying cells; subsequently suppressor T cells return the immune system to normal by inactivating the B cells and killer T cells.

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T-cell British  

noun

1. another name for T-lymphocyte

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T cell Scientific  

1. Any of the lymphocytes that develop in the thymus gland and that act in the immune system by binding antigens to receptors on the surface of their cells in what is called the cell-mediated immune response. T cells are also involved in the regulation of the function of B cells.

2. Also called T lymphocyte

3. See more at cell-mediated immune response Compare B cell

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T-cell Cultural  

1. Key to the immune system, these cells originate in the bone marrow but mature in the thymus (the t stands for thymus). T-cells attack other body cells that are infected by some bacteria, a virus, or another pathogen. (Compare B-cell.)

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Discover More

T-cell counts are used as a diagnostic test to indicate the strength of the immune system in AIDS patients.

The HIV/AIDS virus destroys a type of T-cell, leading to the syndrome characterized by a defective immune system.

Etymology

Origin of T cell

1965–70; T(hymus-derived)

Example Sentences

See Examples For:

T cell T-cell

The study, "SLAMF6 as a drug-targetable suppressor of T cell immunity against cancer," by André Veillette and colleagues, was published in Nature.

From Science Daily ● Jun. 9, 2026

Using a standard booster approach in mice, both vaccine types produced similar antiviral T cell and antibody-producing B cell responses.

From Science Daily ● Mar. 17, 2026

A major breakthrough came from constructing a detailed genetic atlas that maps a range of CD8 T cell states.

From Science Daily ● Mar. 5, 2026

To understand how these immune states are controlled, the researchers examined nine distinct CD8 T cell conditions using advanced laboratory methods, genetic tools, mouse models, and computational analysis.

From Science Daily ● Mar. 5, 2026

This shift in immune cell production boosts T cell activity and changes how immune cells interact within areas where cancer spreads.

From Science Daily ● Jan. 23, 2026

Pending further updates, the news reduces the likelihood that the Swiss drugmaker’s next-generation cell-therapy platform—which aims to accelerate the process of T-cell expansion to treat autoimmune diseases—could provide a future boost, the analysts say.

From The Wall Street Journal ● Sep. 2, 2026

For the first clinical trial evaluating both the safety and effectiveness of CD19 CAR T-cell therapy in rheumatoid arthritis, the Charité team initially enrolled six patients with especially severe disease.

From Science Daily ● Aug. 30, 2026

He battled Stage 3 angioimmunoblastic T-cell lymphoma, a rare and aggressive type of non-Hodgkin lymphoma.

From Los Angeles Times ● Jul. 15, 2026

Gao died on July 7, at 55, of T-cell lymphoma.

From The Wall Street Journal ● Jul. 14, 2026

Key assets include the in vivo CAR-T candidate and T-cell engagers targeting multiple myeloma and ovarian cancer.

From Barron's ● Jun. 26, 2026