T cell

With the B cell, one of the two main types of white blood cell, essential parts of the immune system. T cells originate in the bone marrow, mature in the thymus, and travel in the blood to other lymphoid tissues, such as the spleen, tonsils, and lymph nodes. Through receptor molecules on their surfaces, T cells directly attack invaders (antigens) by binding to them and helping remove them from the body. Because the body contains millions of T and B cells, many of which carry unique receptors, it can respond to virtually any antigen. See also antibody, immunology.