What Is Adaptive Immunity?

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  • Written By: Tricia Ellis-Christensen
  • Edited By: O. Wallace
  • Last Modified Date: 19 April 2014
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Adaptive immunity is an important part of the immune system that governs how the body responds to infectious agents or antigens to which it has been previously exposed. Past exposure to an antigen in either its natural or created forms may create a memory of the antigen’s presence. Future exposure, once adaptive immunity or specific immunity is acquired, results in a quick and effective response. The body mobilizes B and T cells to fight subsequent exposures before they create illness and the person remains well. This brief description presupposes that specific, adaptive or acquired immunity is functioning normally, which isn’t always the case.

There are two main elements of the immune system, which are broken down into innate and adaptive immunity. Innate immunity is the body’s natural response to any exposure to an antigen. The healthy person’s innate immune system works in a variety of ways to fight any disease exposure and end illness, though it isn’t always successful. In contrast, adaptive immunity is developed through antigen exposure or interventions like vaccination. It’s usually faster and more effective, but it is also antigen-specific. It only works when the body has memory of fighting a specific germ before.


Adaptive immunity depends on the body recognizing an antigen to which it has been previously exposed. When that recognition occurs, the body shifts into a high-geared response that can defeat the antigen’s ability to take hold and result in sickness. This response isn’t always perfect, and some people develop partial immunity to illnesses and aren’t able to fully fight them. Also, adaptive immunity to some things can wear off over time, or certain types of viruses and bacteria don’t cause adaptation through exposure.

People with autoimmune diseases may have inappropriate adaptive immunity responses. The body may view any substance, even part of itself, as foreign, and mobilize B and T cells to attack itself. Over time, severe damage can occur, and these illnesses need to be treated with medications that dull both types of immune response.


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