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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

Its surface is covered with antibodies that recognize CD3, a protein found exclusively on T cell surfaces.

From Science Daily ● Oct. 7, 2026

That evidence suggested that both the dendritic cells and the T cell activation process were originating somewhere outside the brain.

From Science Daily ● Sep. 28, 2026

Personalized T cell treatments require cells to be collected and processed separately for individual patients.

From Science Daily ● Sep. 11, 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

In 2025, during a clinical trial of CAR T-cell therapy, a technique currently used to treat some types of leukaemia and lymphoma, Maya developed a brain injury which Dellanie said left her "profoundly disabled".

From BBC ● Sep. 20, 2026

The approach resembles CAR T-cell therapy, but there is an important difference.

From Science Daily ● Sep. 11, 2026

CAR-T therapy, short for chimeric antigen receptor T-cell therapy, was pioneered in the U.S.

From The Wall Street Journal ● Sep. 7, 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

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

From Los Angeles Times ● Jul. 15, 2026