How Aging Affects The Immune System
As we age, our bodies begin to dysfunction more frequently and generally wear out. The simplest physical activities can leave us feeling stiff and sore. Our reaction times slow. Perhaps most detrimental to our health, however, is our ailing immune system. It causes us to heal more slowly, increases our chances for developing cancer, and makes us vulnerable to more severe infections.
Poor Nutrient Absorption
A large part of our aging immune system is affected by our aging digestive system. The vitamins, minerals, and other nutrients required for immune function are taken straight from the foods we eat. Even if we eat a well-balanced diet, our intestines simply don't function like they did when we were 25. Zinc is an especially vital nutrient whose absorption is affected by aging. It is essential for hundreds of chemical reactions in the body, including those required for synthesizing white blood cells. One method of immune protection is to quickly increase the amount of white blood cells present to overcome an infection. Zinc deficiency is partly responsible for the extended time it takes to heal as we age.
The thymus is one of the few organs dedicated to the immune system. The manager cells of the immune system who tell most other immune cell types what to do and when to do it are called T cells (or thymocytes). Up until adolescence T cells are educated in the thymus, where they learn to distinguish between self (the body's own cells) and nonself (bacteria, viruses, cancerous cells, etc). By middle age, the thymus is about 15% of its maximum size. While the number of T cells doesn't decrease, their function does. This ailing management causes the whole immune system to be less effective.
Slower Production of Antibodies
Antibodies are small proteins secreted by certain immune cells called B cells. They are used to tag harmful organisms or molecules so that phagocytes (cells which ingest things) can devour and destroy them. To mount an effective response, B cells must proliferate to create enough antibodies. As we age, our B cells proliferate more slowly, leading to a slower production of antibodies and therefore a weaker immune response.
Decreased "Self" Tolerance
Aging T cells also become less capable of differentiating between self and nonself, often causing the production of autoantibodies. As a result we become more susceptible to autoimmune diseases as we age, such as rheumatoid arthritis. Conditions like atherosclerosis are also caused by the damage of autoantibodies.
Less Effective Surveillance
Several kinds of immune cells are responsible for monitoring self cells to make sure they are disease-free. Cells which begin to act cancerous (multiple uncontrollably or produce certain chemicals) or are infected with a bacterium or virus are destroyed to prevent spread. The immune cells responsible for such detection become less effective as we age, leading to an increased chance of cancer development. Elderly people are also less able to quickly fight off viral infections because of these ailing immune cells. While many of the above circumstances are unavoidable, getting ample nutrition as well as keeping stress at a minimum can help your immune system to function most effectively.