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Science

Defending against infection

Immunity

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

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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