Psychoimmunologic and endorphin function in the aged.

Abstract

In humans and all mammalian species which have been studied so far, the immune system undergoes significant changes with advancing age.I4 Immunosenescence may be defined as those alterations in immune function which occur to some degree in all older individuals, and which are distinguishable from immunodeficiency secondary to underlying disease, malnutrition, toxic exposure, or genetic disorder. The increased incidence of malignancy, infectious disease, autoimmune disorders, monoclonal gammopathies, and amyloidosis with age is felt to be linked with this decline of immunocompeten~e.~~ In addition, the immunologic theory of aging' proposes genetically programmed changes in immune cells as the determinant of maximum lifespan. Support for this theory may be found in the fact that intervention which increases the lifespan of rodents (dietary restriction, hypothermia) also causes profound changes in immune Conversely, in humans, derangements of immunity such as high autoantibody low suppressor cell activity, and impaired cutaneous hypersensitivity l6 have been correlated with increased mortality. Immunosenecence is characterized by its high prevalence, interindividual variability, and complexity. The immune system is not uniformly affected by the aging process. For example, total numbers of white blood cells, lymphocytes, and granulocytes, as well as phagocytic function of neutrophils and the complement system do not change appreciably with The most significant decrements occur in cellular immunity, in such functions as delayed type hypersensitivity,2 resistance to tumor cells,Z' viruses and protozoans,6'* primary allograft rejection, and graft versus host