MSD Manual

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Effects of Aging on the Immune System

By

Peter J. Delves

, PhD, University College London, London, UK

Medically Reviewed Sep 2021 | Modified Sep 2022
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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.

NOTE: This is the Consumer Version. DOCTORS: VIEW PROFESSIONAL VERSION
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