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

Constant exposure to the unfriendly and immunosuppressive environment around the tumor impairs white blood T cells and forces them into an exhausted, dysfunctional state. —William A. Haseltine, Forbes, 25 Oct. 2024

For example, if CAR T cells target a different protein or target two proteins at once, the treatment may more throughly eliminate cancer cells. —William A. Haseltine, Forbes, 13 Sep. 2024

Rao and his colleagues identified CD4 T cells — or pathogenic T cells — as the ones causing an imbalance of B cells. —Joshua Rapp Learn, Discover Magazine, 10 Sep. 2024

Fortunately, immunity from past exposure, in the form of memory T cells, keeps most people from getting severely ill. —Tanya Lewis, Scientific American, 16 July 2024

Word History

Etymology

thymus-derived cell

First Known Use

1970, in the meaning defined above

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