Treating Disease What are monoclonal antibodies Polyclonal antibodies

Treating Disease

What are monoclonal antibodies? Polyclonal antibodies are naturally produced in an immune response. Different plasma cells secrete antibodies, resulting in a variety of different antibodies against a specific antigen. Monoclonal antibodies (m. Abs) are antibodies produced from clones of a single plasma cell and are therefore all identical. They have many important uses, such as: l the treatment of cancer and other diseases l drug screening l home pregnancy kits l scientific research.

Production of monoclonal antibodies Large quantities of m. Abs can be produced using mice or rabbits. A specific antigen is injected into the animal, stimulating the production of plasma cells. The plasma cells are removed from the animal and fused with cancerous myeloma cells from normal mice. These form immortal hybridoma cells, which can produce a single type of antibody indefinitely.

Exam question – monoclonal antibodies Remember: - Antigen injected into animal - Plasma cells produced - Plasma cell fused with myeloma (cancer) cell - Hybridoma cell formed – multiplies quickly and indefinitely to produce many identical antibodies (for the original antigen).

Artificial immunity 6 of 38 © Boardworks Ltd 2008

Vaccines, lymphocytes and the secondary response Primary Response Secondary Response The first time a new antigen is The second time the antigen encountered, it takes time for is encountered, there already a number of memory B- and T-cells to respond. cells present. Antibodies are produced fairly The immune response is slowly as plasma cells are produced by mitosis of B-cells. quicker. Memory cells (B and T) remain in the blood for a period of time after the initial infection. More antibodies are produced more quickly than in the primary response.

Immunological memory

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Influenza vaccines New strains of the influenza virus are constantly emerging. This is because antigens displayed on the virus change due to mutation. This causes antigenic variation. Antigenic variation makes it hard to immunize a patient against the influenza virus for life with just a single vaccine. The government works with other organizations to identify current strains of influenza. An effective vaccine is developed each year. 10 of 38 © Boardworks Ltd 2008

What is vaccination? Vaccines stimulate the production of antibodies and memory cells against the target pathogen without causing illness. Why don’t vaccines cause illness? l They may contain an inactivated form of the pathogen, killed by heat treatment (which leaves the immune -stimulating antigens intact). l They may contain an attenuated (less virulent) form of the pathogen. l They may contain isolated antigens, such as cell surface proteins, from the pathogen. 11 of 38 © Boardworks Ltd 2008

The MMR controversy In 1998, a scientific paper was published in the medical journal The Lancet, speculating that the MMR vaccine could cause autism. The authors thought that the MMR vaccine could damage the bowel, allowing toxins that are normally destroyed in digestion to move into the blood. If these toxins travelled to the brain they might cause autism. The authors did not prove that this was the case but still recommended that doctors stop administering the MMR vaccine until more research was done. 13 of 38 © Boardworks Ltd 2008

The media’s role in the MMR controversy Many studies have concluded that the MMR vaccine is safe and only a few studies claim that it isn’t. However, this was not reflected by the media coverage. The majority of coverage centred on the possibility of a link between the MMR vaccine and autism, while the government insisted that the vaccine was safe. This mixed message caused confusion among the general public, leading to a drop in the number of children being given the combined vaccine. Should scientists be more careful about how they present their research or should the media be responsible for how they present controversial topics to society? 14 of 38 © Boardworks Ltd 2008