T cell
Meaning of T cell: A T cell is an immune cell, matured in the thymus, that attacks infected or abnormal cells or helps direct the immune response.
Definition of T cell
A T cell is a type of white blood cell that plays a central role in the immune system's ability to identify and respond to threats. T cells develop in the bone marrow but mature in the thymus, a gland located in the chest, which is the source of the letter T in the cell's name.
Different types of T cells serve different functions. Cytotoxic T cells directly attack cells infected with a virus or cells that have become cancerous, while helper T cells coordinate the broader immune response by signaling to other immune cells, including those responsible for producing antibodies.
Because T cells are involved in recognizing both foreign invaders and the body's own abnormal cells, conditions that reduce their number or function, including certain infections and some medications, can leave a person vulnerable to infections and other illness that a properly functioning immune system would normally control.
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Used in a sentence
Laboratory testing measured the patient's T cell count as part of the immune system evaluation.
Good to know
A T cell is distinguished from a B cell chiefly by where each matures and by its role, since T cells act directly against abnormal cells or coordinate the immune response, while B cells mainly produce antibodies.