What is innate immunity?

Innate immunity is the body's immediate immune system response to a perceived threat. Invaders such as bacteria, viruses and other microorganisms display "signs" on their surface called antigens that signal immune system cells to action.

The innate immune system includes visible protection, such as your skin and the mucus membranes in your nose and mouth that strain out pathogens, and invisible protection in the form of white blood cells such as macrophages, which release inflammatory chemicals such as histamine and leukotrienes to destroy invaders. Sometimes this process runs amok, as when the innate immune system launches an all-out attack against harmless proteins like those from pollen or peanuts, resulting in an allergic reaction.

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