Immunity

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Definitions

Description

Immunity is a biological term that describes a state of having sufficient biological defenses to avoid infection, disease, or other unwanted biological invasion. Immunity involves both specific and non-specific components. The non-specific components act either as barriers or as eliminators of wide range of pathogens irrespective of antigenic specificity. Other components of the immune system adapt themselves to each new disease encountered and are able to generate pathogen-specific immunity.

Adaptive immunity is often sub-divided into two major types depending on how the immunity was introduced.

Passive immunity is acquired through transfer of antibodies or activated T-cells from an immune host, and is short lived -- usually lasting only a few months Active immunity is induced in the host itself by antigen, and lasts much longer, sometimes life-long.[1]

See also