Effects of aging on immune function.

A variety of changes are observed in the immune system in both animals and humans with increasing age. There is a decline in the functional capacity of the cell populations that mount generalized and focused immune responses, and decreasing production and response of these cells to regulatory signals and proteins. These changes translate into less effective innate and adaptive immune responses, increased reactivity against self-antigens in vivo, and an increased incidence of infection. There may also be an increased risk of mortality. The mechanisms underlying age-related changes in immune function are not fully understood, but are likely to be multifactorial, including environmental and behavioral factors that affect over-all immune function from the molecular level to that of the entire organism.