Antibodies are produced by white blood cells called B- lymphocytes. Pathogens have a substance on their surface called an antigen that stimulates an immune response, examples are viruses and bacteria. When a foreign pathogen enters the body, its antigen binds to the B-lymphocyte surface.
It causes the B-lymphocytes to divide and create clones called plasma cells. These plasma cells secrete millions of antibodies into the bloodstream 12. Each type of antibody is different depending on the pathogen they are targeting. They have an antigen binding region exclusive to the antigens on the bacteria or virus. Once attached to the antigens they begin to attack the pathogen by neutralising it.
This can arise in several ways. Firstly, it can make the pathogen immobile preventing it from travelling and entering host cells. Antitoxins can change the chemical composition of the antigen by counteracting the toxins produced by the antigen 12How antibodies are made in the lab Polyclonal antibodies are all different to each other. They can be produced in a lab by a process where a safe injection containing a specific antigen is injected into a mouse or rabbit. This triggers an immune response and antigen-specific plasma cells are produced with specific antibodies.
The antibodies can be removed from the mouse by a blood sample. It is cheap to produce a polyclonal population. A monoclonal population is where all the antibodies are identical and they can be produced by Hybridoma. Hybridoma is when a specific antigen is injected into a mouse. Antibody-producing plasma cells are extracted from the mouse’s spleen and diffused with a tumor cell called melanoma. The cells multiply and produce specific, identical antibodies each time the cell divides. This is an expensive technique but is essential for diagnostics and therapeutics.
13Monoclonal antibodies recognize specific proteins on cells, particularly cancer cells. Each monoclonal antibody detects a protein on the antigen of the cell. Once the antibodies are attached to the proteins, it triggers the immune system and stimulates an immune response in order to attack and kill cancer cells (Figure 6 – Monoclonal antibodies and cancer cells). An example of monoclonal antibodies is trastuzumab that is used to treat breast cancer 14.