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The '''immune system''' is the complex system in the body responsible for fighting disease. Its primary function is to identify foreign substances in the body ([[bacteria]], [[viruses]], [[fungi]] or [[parasites]]) and develop a defense against them. This defense is known as the immune response.  

The '''immune system''' is the complex system in the body responsible for fighting disease. Its primary function is to identify foreign substances in the body ([[bacteria]], [[viruses]], [[fungi]] or [[parasites]]) and develop a defense against them. This defense is known as the immune response.  

It involves [[white blood cells]] and the production of [[protein]] molecules called [[antibodies]] to eliminate foreign organisms that invade the body.<ref>http://www.cdc.gov/vaccines/about/terms/glossary.htm#i</ref>

It involves [[white blood cells]] and the production of [[protein]] molecules called [[antibodies]] to eliminate foreign organisms that invade the body.<ref>https://www.cdc.gov/vaccines/about/terms/glossary.htm#i</ref>

==References==

==References==