B cell (B lymphocyte) A lymphocyte that is derived from stem cells in the bone marrow but does not mature in the thymus (compare T cell); in birds it matures in the bursa of the cloaca (hence B cell). Each B cell has a unique set of receptor molecules on its surface, designed to recognize a specific antigen. Binding of the appropriate antigen to class II MHC receptors on the B cell (see histocompatibility) is recognized by helper T cells, which themselves bind to the antigen–receptor complex. This triggers the T cells to release lymphokines, which cause the B cell to undergo repeated division to form a clone of cells (i.e. clonal expansion). These mature into plasma cells, capable of producing large amounts of specific antibody (see immunoglobulin), which circulates in the blood and lymph and binds to the corresponding antigen. After a few days of antibody production the plasma cells die. However, some cells from the clone remain in the form of memory cells, which initiate a more rapid immune response on subsequent exposure to the same antigen. See also clonal selection theory.
More From encyclopedia.com
T Cell , T cell T cell (T lymphocyte) Any of a population of lymphocytes that are the principal agents of cell-mediated immunity. T cells are derived from the… Schwann Cell , Schwann cell (neurilemma cell) A cell that forms the myelin sheath of a nerve fibre. Each cell is responsible for a single length of the fibre (calle… Adherens Junction , adherens junction A cell junction that is commonly observed in epithelial (see EPITHELIUM) cells (e.g. those lining the intestine and those in cardia… Cell Membrane , cell membrane (plasmalemma, plasma membrane, protoplast) A sheet-like membrane, 7.5–10 nm thick, that forms a selectively permeable barrier enclosing… Cell Death , Cell death Like all living things, the various types of cells in plants, animals, and the many different cell types in humans eventually die. Cell de… killer cell , killer cell Either of two types of lymphocyte that destroy infected or cancerous host cells. Natural killer cells are distinct from both T cells and…
About this article
All Sources -
Updated About encyclopedia.com content Print Topic
You Might Also Like