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

The research also has helped scientists zero in on a specialized type of T cells, called Th2 cells, as the main targets of allergy immunotherapy. —Ashley MacKin Solomon, San Diego Union-Tribune, 5 Aug. 2025

The researchers also found heightened inflammatory responses in T cells (a type of white blood cell) known as MAIT. —New Atlas, 25 July 2025

Here, melanoma cancer treatments delivered using C-a16 were three times more effective at shrinking tumors and boosted the destructive power of cancer-fighting T cells. —Stephanie Edwards, Discover Magazine, 22 July 2025

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

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