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Defending against infection


Pathogens contain certain chemicals that are foreign to the body. These chemicals are called antigens. Certain white blood cells, called lymphocytes, can produce specific antibodies to kill a particular pathogen.


Antibodies are proteins. They can neutralise pathogens in a number of ways. For example, they can:

  • bind to pathogens and damage or destroy them
  • coat pathogens, clumping them together so that they are easily ingested by white blood cells called phagocytes.

Each lymphocyte produces a specific type of antibody - a protein that has a chemical 'fit' to a certain antigen. When a lymphocyte with the appropriate antibody meets the antigen, the lymphocyte reproduces quickly and makes many copies of the antibody to kill the pathogen.

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