Aging and the immune system

ABSTRACT

The elderly are more susceptible to illness than young adults. Ageing is associated with varied immune response deficits involving cellular and humoral immunity. There are important age related changes into the T-cell compartment which may leave older patients relatively immunosuppressed. Thymic involution is strongly implicated in contributing to the age related loss of high affinity antibody response. In elderly humans and animals, there is a generalised decline into the ability to respond, and in fact the decline begins before an animal is half way through its normal lifespan. This decline can be measured in many immune phenomena. Both failure of helper T-cells and an increase in suppressor T-cell activity may contribute to the waining of the antibody response. Age related increase in cancer may be yet another manifestation of immune senescence. Since the ageing immune system may have a permissive role in diseases causing premature death, these ageing changes could actually determine the altimate life span of the species. Thus any intervention restoring normal immune function might indeed prolong life. If however, thymic involution serves physiologic compensatory role by protecting against autoimmune disease and keeping the immune system in check, thymic restoration could even accelerate the ageing process via autoimmune reactions