Antibodies themselves don't secrete anything; instead, they are secreted by other cells. Specifically, plasma B cells, a type of white blood cell, are responsible for producing and releasing antibodies into the bloodstream. These antibodies then bind to specific foreign substances, called antigens, to help neutralize them.
The Role of Plasma B Cells
Plasma cells are the terminally differentiated form of B cells. As described in "The generation of antibody-secreting plasma cells | Nature Reviews Immunology," plasmablasts, the precursors to plasma cells, initially produce and secrete smaller amounts of antibodies. Mature plasma cells, however, are highly specialized antibody factories, focusing solely on antibody production and secretion. Their primary function, as noted in "Histology, Plasma Cells - StatPearls - NCBI Bookshelf," is the large-scale, sustained production of antibodies.
- Antibody Production: Plasma cells synthesize antibodies in massive quantities.
- Antibody Secretion: These antibodies are then released into the bloodstream and other bodily fluids.
- Antigen Binding: Once released, antibodies bind to specific antigens, marking them for destruction by other immune cells.
Different Types of Antibodies and Their Secretion
While all antibodies are secreted by plasma cells, different types exist, each with slightly varied functions and secretion patterns. The initial antibodies produced by a newly formed B cell are not secreted; instead, they are membrane-bound and act as receptors. (B Cells and Antibodies - Molecular Biology of the Cell - NCBI) Later, upon activation, the B cell differentiates into a plasma cell, which secretes the free-floating antibodies. ("Antibodies: Definition, Types & Function")
The timing and amount of antibody secretion also vary based on the type of immune response and the specific antigen. As stated in "Long-Lived Plasma Cells Secrete High-Affinity Antibodies," long-lived plasma cells consistently secrete high-affinity antibodies over extended periods.
In Summary
Antibodies are proteins secreted by plasma B cells, a crucial part of the adaptive immune system. They do not themselves secrete anything, but rather are the secreted products of these specialized immune cells.
