Aging changes in immunity
Information:
BACKGROUND
Aging is not synonymous with illness. However, aging does increase the risk for certain illnesses. Overall, elderly people have an increased rate of chronic disorders, infections, autoimmune disorders, and cancer.
This increased risk may be caused, in part, by the nature of these disorders. Most of the chronic disorders such as arteriosclerosis are slowly progressive and do not show symptoms until well along. Another significant part of this increased risk is probably related to aging changes in the immune system.
The immune system protects against diseases. It seeks out and destroys viruses, bacteria, fungi, cancerous cells, and so on before they can damage the body. It learns to tell the difference between "self" tissue and "non-self" particles.
AGING CHANGES
The thymus, one of the organs of the immune system, begins to shrink (atrophy) after adolescence. By middle age it is only about 15% of its maximum size. This is the site where certain immune cells (called T lymphocytes or T cells) mature.
Some of the T cells directly kill foreign particles. Some T cells help control other parts of the immune system. Although the number of T cells does not decrease with aging, T cell function lessens. This, in turn, decreases the functioning of the parts of the immune system controlled by T cells.
EFFECT OF CHANGES
There is a slow, steady decrease in immunity after young adulthood. When the body is exposed to bacteria or other microorganisms (from an actual exposure or an immunization), less of the protective antibodies may be formed or they may be formed at a slower rate. Flu shots or other immunizations may be less effective, and protection may not last as long as expected.
Later in life, the immune system seems to become less tolerant of the body's own cells. Sometimes normal tissue is "mistaken" for non-self tissue, and autoimmune disorders develop. The immune system becomes less able to detect malignant cells, and cancer risk increases with age.
The immune system also becomes less able to detect foreign particles, and infection risk is greater. Other things also increase the risk of infections. Sensation changes, gait changes, changes in the skin structure, and other "normal changes" increase the risk of injury, and bacteria can enter through nonintact skin. Having an illness or surgery can further weaken the immune system, making the body more susceptible to subsequent infections.
Besides slightly decreased immunity, aging also affects inflammation and wound healing. Many older people heal slower and have more problems with healing. This may be directly related to changes in the immune system, or it may be a consequence of other problems such as diabetes or arteriosclerosis. Also, many older people take anti-inflammatory medications (to control conditions such as arthritis) and these are also known to slow wound healing.
COMMON PROBLEMS- increased infection risk
- decreased ability to fight diseases
- slowed wound healing
- autoimmune disorders
- cancer
DISEASE PREVENTION
Just as routine immunizations are important to prevent illness in children, a few routine immunizations are important as we get older. Adult tetanus (Td) immunizations should be given every 10 years (a booster may be given sooner if there is a "dirty" wound). Your health care provider may recommend other immunizations, including pneumovax (to prevent pneumonia), flu vaccine, hepatitis immunization, or others. These optional immunizations are not necessary for ALL older people, but are appropriate for some.
Keeping generally healthy also helps. Exercise, eat right, reduce or stop smoking, and minimize alcohol use. Use safety measures to avoid falls and other injuries.
RELATED TOPICS
aging changes in hormone production
aging changes in organs, tissues, and cells
aging versus disease
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The information provided herein should not be used for diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Copyright 2000 adam.com, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
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