T cell

noun

: any of several lymphocytes (such as a helper T cell) that differentiate in the thymus, possess highly specific cell-surface antigen receptors, and include some that control the initiation or suppression of cell-mediated and humoral immunity (as by the regulation of T and B cell maturation and proliferation) and others that lyse antigen-bearing cells : t lymphocyte

The immature lymphoid cell, in turn, can be processed into a B cell, which makes infection-fighting antibodies, or a T cell, which recognizes foreign tissue and virally infected cells and directs the activities of the rest of the immune system.

—Gina Kolata

T cells recognize antigen only in association with cell surface molecules encoded by the major histocompatibility complex …

—Miranda Robertson

see helper t cell, killer t cell compare b cell

Examples of T cell in a Sentence

Recent Examples on the Web

According to the National Cancer Institute, Car T-cell therapy involves genetically engineering a patient’s own T cells – part of the body’s immune system – to attack cancer cells. —Ben Morse, CNN Money, 17 July 2025

However, for the treatment to be effective, those T cells need to be in peak fighting condition and not exhausted. —New Atlas, 16 July 2025

Since too much momentum and the release of cytokines proteins can harm the body, having switchable CAR T cells can curb negative impacts. —Noah Lyons, San Diego Union-Tribune, 15 July 2025

According to the researchers, cats treated with MSC therapy had fewer overly active T and B cells (which are associated with immune overdrive) and more regulatory T cells (which can calm the immune system). —Jack Knudson, Discover Magazine, 15 July 2025

Word History

Etymology

thymus-derived cell

First Known Use

1970, in the meaning defined above

Rhymes for T cell

• bel
• belle
• cel
• dell
• dwell
• el
• ell
• fel
• fell
• gel
• gell
• jell

Kids Definition

T cell

noun

: any of the lymphocytes (as a helper T cell) that usually mature in the thymus and take an active part in immune responses compare b cell

Medical Definition

T cell

noun

: any of several lymphocytes (as a helper T cell) that differentiate in the thymus, possess highly specific cell-surface antigen receptors, and include some that control the initiation or suppression of cell-mediated and humoral immunity (as by the regulation of T and B cell maturation and proliferation) and others that lyse antigen-bearing cells

called also T lymphocyte

see cytotoxic t cell, helper t cell, suppressor t cell, t4 cell