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

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

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

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

To address this age related decline, scientists from MIT and the Broad Institute developed a method to temporarily reprogram liver cells in a way that strengthens T cell performance.

From Science Daily • Dec. 29, 2025

Although he went on to study cancer, developmental disabilities and ultimately leprosy, the T cell remained at the heart of his scientific inquiries.

From The Wall Street Journal • Dec. 23, 2025