Immunity
- Date: 14th century
Definitions
- 1 : the quality or state of being immune; especially : a condition of being able to resist a particular disease especially through preventing development of a pathogenic microorganism or by counteracting the effects of its products
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.
- Naturally acquired immunity occurs through contact with a disease causing agent, when the contact was not deliberate, whereas
- Artificially acquired immunity develops only through deliberate actions such as vaccination. Both naturally and artificially acquired immunity can be further subdivided depending on whether immunity is induced in the host or passively transferred from a immune host.
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]
