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Effects of Aging on the Immune System

By

Peter J. Delves

, PhD, University College London, London, UK

Last full review/revision Sep 2021| Content last modified Sep 2021
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  • Microorganisms (commonly called germs, such as bacteria, viruses, and fungi)

  • Parasites (such as worms)

  • Cancer cells

  • Transplanted organs and tissues

Newborns

At birth, acquired (specific) immunity Acquired Immunity One of the body's lines of defense (immune system) involves white blood cells (leukocytes) that travel through the bloodstream and into tissues, searching for and attacking microorganisms and... read more Acquired Immunity is not fully developed. However, newborns have some antibodies, which crossed the placenta from the mother during pregnancy. These antibodies protect newborns against infections until their own immune system fully develops. Breastfed newborns also receive antibodies from the mother in breast milk.

Older people

As people age, the immune system becomes less effective in the following ways:

These changes in immune function may contribute to the greater susceptibility of older people to some infections and cancers.

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Test your knowledge
Physical Allergy
A physical allergy is an allergic reaction triggered by a physical stimulus, such as pressure on the skin or minor injury. For some people, symptoms occur only in response to a physical trigger. For other people, the physical trigger worsens responses caused by other allergens.  Which of the following is NOT an example of a physical trigger?
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