T cell

T cells belong to a group of white blood cells known as lymphocytes and play a central role in cell-mediated immunity. They can be distinguished from other lymphocyte types, such as B cells and NK cells by the presence of a special receptor on their cell surface that is called the T cell receptor (TCR). The abbreviation "T", in T cell, stands for thymus since it is the principal organ for their development.
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Noun
1. a small lymphocyte developed in the thymus; it orchestrates the immune system's response to infected or malignant cells
(synonym) T lymphocyte
(hypernym) lymphocyte, lymph cell
(hyponym) helper T cell, helper cell, CD4 T cell, CD4 cell

A white blood cell made in the thymus gland, a lymphoid structure in the upper chest. (The T in T-cell stands for Thymus). The T-cells coordinate the immune system by secreting lymphokine hormones. There are 3 fundamentally different types of T cells : helper, killer, and suppressor. Each has many subdivisions. T-cells are also called T lymphocytes.

One type of white blood cell that attacks virus-infected cells, foreign cells, and cancer cells. T cells also produce a number of substances that regulate the immune response.