T-lymphocyte

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