The immune system of vertebrates help keep the animal healthy by making millions of different proteins (immunoglobulins) called antibodies to disable antigens (harmful foreign substances such as toxins or bacteria). Scientists have worked to develop a method to extract large amounts of specific antibodies from clones (exact copies) of a cell created by fusing two different natural cells. Those antibodies are called monoclonal antibodies.

Antibody research began in the 1930s when the American pathologist Karl Landsteiner found that animal antibodies counteract specific antigens and that all antibodies have similar structures. Research by the American biochemists Rodney R. Porter (1917-1985) and Gerald M. Edelman (1929- ) during the 1950s determined antibody structure, and particularly the active areas of individual antibodies. For their work they received the 1972 Nobel prize in physiology or medicine.

By the 1960s, scientists who studied cells needed large amounts of specific antibodies for their research...