B lymphocyte

B lymphocytes, also known as B cells, are a type of white blood cell that plays a significant role in the immune system. They are named for their discovery in the bursa of Fabricius in birds, but in mammals, they mature in the bone marrow, which is also denoted by the "B" in their name.

Function

B lymphocytes are responsible for humoral immunity, a component of the adaptive immune system. They produce antibodies in response to antigens, which are foreign substances in the body. These antibodies are specific to the antigen that triggered their production, allowing for targeted immune responses.

Development

B lymphocytes originate from hematopoietic stem cells in the bone marrow. They undergo a process of maturation and differentiation, during which they rearrange their immunoglobulin genes to produce a unique antibody. Once mature, they leave the bone marrow and circulate in the bloodstream and lymphatic system.

Activation

When a B lymphocyte encounters its specific antigen, it becomes activated. This process typically requires help from a T helper cell, which binds to the B cell and releases cytokines that stimulate the B cell to divide and differentiate into plasma cells and memory B cells.

Clinical significance

Abnormalities in B lymphocytes can lead to various immune disorders. For example, autoimmune diseases can occur when B cells produce antibodies against the body's own tissues. B cell lymphomas and leukemias are cancers that arise from B cells.

See also

• T lymphocyte
• Immune response
• Antibody production