TLymphocyte

T lymphocytes, often called T cells, are a type of white blood cell that plays a crucial role in the adaptive immune system. They are a type of lymphocyte, a broader category of immune cells that also includes B cells and natural killer cells. T cells are produced in the bone marrow and mature in the thymus, a small gland located behind the sternum. This maturation process is essential for T cells to develop their specific functions and to prevent them from attacking the body's own tissues.

There are several distinct types of T cells, each with a specialized function. Helper T cells (also known as CD4+ T cells) are critical for coordinating the immune response. They activate other immune cells, including B cells to produce antibodies and cytotoxic T cells to kill infected cells. Cytotoxic T cells (also known as CD8+ T cells) are responsible for directly killing cells that have been infected by viruses or other pathogens, as well as abnormal cells like cancer cells. Regulatory T cells (also known as suppressor T cells) help to prevent the immune system from overreacting and attacking healthy tissues, thus maintaining self-tolerance.

T cells recognize specific antigens, which are molecules typically found on the surface of pathogens or abnormal cells. This recognition is mediated by the T cell receptor (TCR), a protein complex on the surface of the T cell. When a T cell encounters an antigen that matches its TCR, it becomes activated. This activation triggers a cascade of events leading to the T cell multiplying and differentiating into effector cells that can combat the specific threat. The precise targeting of T cells makes them a vital component of immune defense against a wide range of diseases.