T cell

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.

T-cell

noun

1. another name for T-lymphocyte

T cell

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

T-cell

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.)

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.

Word History and Origins

Origin of T cell¹

1965–70; T(hymus-derived)

Example Sentences

This is because mRNA vaccines induce the immune system to make both antibodies and specialized immune cells called T cells.

From Salon

According to the American Cancer Society, PD-1 is a protein that acts as an “off switch” to keep certain immune cells — T cells — from attacking normal cells.

From Los Angeles Times

NIH funding supported, among others, the development of CAR T cell therapy, which genetically modifies a patients’ own T-cells to fight cancer.

From Los Angeles Times

Among the SLAM-expressing cells that measles wrecks are memory B and T cells, two crucial players in a functioning immune system.

From Los Angeles Times

“T cells are activated by little pieces of bacterial and viral proteins, called peptides, that get displayed on the surface of infected cells,” Hand explained.

From Salon