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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

Mice vaccinated with the mRNA cancer vaccine still generated strong T cell responses even when they lacked cDC1 cells.

From Science Daily ● Jul. 9, 2026

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

Earlier research connected T cell diversity to aging and declining immune function, but those studies were typically small and focused on blood samples.

From Science Daily ● Jun. 1, 2026

Over time they can enter a dysfunctional condition called T cell exhaustion, where their ability to eliminate threats declines.

From Science Daily ● Mar. 5, 2026

Earlier efforts to rejuvenate the immune system have often focused on sending T cell growth factors through the bloodstream, but that approach can cause harmful side effects.

From Science Daily ● Dec. 29, 2025

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

He used his remission to promote CAR T-cell therapy, which genetically alters one’s cells to fight cancer, after he said chemotherapy stopped working.

From Los Angeles Times ● Jul. 13, 2026

The results suggest a possible path toward improving treatment for cancers that currently respond poorly to CAR T-cell therapy, particularly solid tumors.

From Science Daily ● Jun. 2, 2026

The actor was treated with CAR T-cell therapy, which uses a disabled virus to genetically reprogram human infection-fighting T-cells, enabling them to target specific cancers.

From Barron's ● Apr. 29, 2026