Antibodies, proteins that identify and destroy foreign particles such as bacteria, are produced by the white blood cells of the body. There are five different types of white blood cells, also called leukocytes, that provide the body with immunity but it is the lymphocytes that are responsible for producing antibodies.
Antigen Processing
When bacteria or viruses invade the body they send out chemical signals that are received by white blood cells. The white blood cells then move into action migrating toward the site of infection. Once at the infection site, monocytes, which are the largest of all the white blood cells according to Blood: The River of Life, squeeze through the walls of the blood vessels and enter the affected tissue. Once in the tissue, monocytes are called macrophages. These macrophages eat the bacteria revealing the proteins, also called antigens, inside.
Antigens are proteins specific to each type of foreign particle. These proteins may function as either toxins or enzymes (substances that speed up reactions). These antigens are then recognized by lymphocytes.
B Cell Stimulation
There are two types of lymphocytes. B lymphocytes are produced in the bone marrow and remain there to become mature. T lymphocytes are produced in the bone marrow but then move to the thymus, an organ of the immune system located in the chest cavity in front of the heart, to mature. Each lymphocyte is specialized to recognize only one specific antigen.
Once the antigens are presented by the macrophages, the B lymphocytes with receptors specific for that antigen flood the site. The B lymphocytes then begin to digest the antigen breaking it down into smaller fragments. T lymphocytes, known as helper T cells, also move into the site of infection. When these helper T cells 'see' the same antigen on the macrophages and the B lymphocytes, they bind to the B lymphocyte and secrete cytokines, also called lymphokines.
Antibody Production
The secretion of lymphokines stimulates the B lymphocytes to divide by repeated mitosis. Mitosis is the division of a cell that results in two identical daughter cells. Each cell produced is an exact replica and recognizes and binds to the same antigen. These new cells differentiate into plasma cells, cells whose main function is to produce antibodies. The plasma cells secrete their receptors that recognize the antigen, which is now called the antibody. The antibodies mark the foreign substance and may either kill it directly or just make it easier for the other white blood cells to destroy it as described by Cells Alive.
