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

But what if the CAR T cells could be altered to withstand the ovarian tumor environment? —William A. Haseltine, Forbes, 31 Oct. 2024

The thymus, which produces infection-fighting T cells, reaches its peak size at puberty and then steadily shrinks. —Lisa M. Krieger, The Mercury News, 29 Oct. 2024

Many of the current options broadly suppress the immune system, including beneficial T cells that fight infection. —Aria Bendix, NBC News, 10 July 2024

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

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