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

T cells are taken from the patient's blood and genetically altered in a lab before being returned to the patient's blood, according to the American Cancer Society. —Rachael O'Connor, MSNBC Newsweek, 12 Sep. 2025

This is because mRNA vaccines induce the immune system to make both antibodies and specialized immune cells called T cells. —Deborah Fuller, CNN Money, 10 Sep. 2025

This is because mRNA vaccines induce the immune system to make both antibodies and specialized immune cells called T cells. —Deborah Fuller, The Conversation, 3 Sep. 2025

When tested on human T cells, which had been developed to recognize a range of tumor antigens, zeaxanthin bolstered the immune cells' power in killing off melanoma, multiple myeloma and glioblastoma cells. —New Atlas, 3 Sep. 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