9^th European Immunology Conference

T-Cells and B-Cells

T cell: A type of white blood cell that is of key importance to the immune system and is at the core of adaptive immunity, the system that tailors the body's immune response to specific pathogens. The T cells are like soldiers who search out and destroy the targeted invaders. Immature T cells (termed T-stem cells) migrate to the thymus gland in the neck, where they mature and differentiate into various types of mature T cells and become active in the immune system in response to a hormone called thymosin and other factors. T-cells that are potentially activated against the body's own tissues are normally killed or changed ("down-regulated") during this maturational process. There are several different types of mature T cells. Not all of their functions are known. T cells can produce substances called cytokines such as the interleukins which further stimulate the immune response. T-cell activation is measured as a way to assess the health of patients with HIV/AIDS and less frequently in other disorders. T cell are also known as T lymphocytes. The "T" stands for "thymus" -- the organ in which these cells mature. As opposed to B cells which mature in the bone marrow. B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system by secreting antibodies. Many B cells mature into what are called plasma cells that produce antibodies (proteins) necessary to fight off infections while other B cells mature into memory B cells. All of the plasma cells descended from a single B cell produce the same antibody which is directed against the antigen that stimulated it to mature. The same principle holds with memory B cells. Thus, all of the plasma cells and memory cells "remember" the stimulus that led to their formation. The maturation of B cells takes place in birds in an organ called the bursa of Fabric’s. B cells in mammals mature largely in the bone marrow. The B cell, or B lymphocyte, is thus an immunologically important cell. It is not thymus-dependent, has a short lifespan, and is responsible for the production of immunoglobulins. It expresses immunoglobulins on its surface.