Question

Explain why during aging the immunological space in your body becomes filled with memory cells. Explain why this might be an advantage and a disadvantage to your body.

Answer 1

The competency of adaptive immune function decreases with age, primarily because of the decline in production of naive lymphocytes in the bone marrow and thymus as well as expansion of incompetent memory lymphocytes.

The adaptive immune system is equipped with 2 key weapons: enormously diverse antigen recognizing lymphocyte populations (naive lymphocytes) and very long lived antigen experienced lymphocytes (memory lymphocytes).

Naive lymphocytes ensures a specific response to any potential challenges from foreign antigens and the memory lymphocytes guarantees a more rapid and robust response to subsequent encounters of a previously experienced antigen.

Despite a continuous decline in the generation of naive lymphocytes and an imperfect maintenance of memory lymphocytes after puberty, the adaptive immune system adjusts to these age associated changes and protects the body successfully against most pathogens for nearly all of adult life.

Only in the late phase of life does the progressive decline of immune function create vulnerability, with a resultant increase in morbidity and mortality due to infection in the elderly.

Immunosenescence describes a state of profound age associated changes in the immune system, these changes are manifested by the overall decline of the antigen-specific immunity.

At the cellular level, the most prominent features of immunosenescence include a substantial decrease in the number of naive lymphocytes, as a result of a reduction in the mic output of T cells as well as fewer bone marrow early progenitor B cells and an accumulation of functionally incompetent memory lymphocytes.

As the direct consequence of these changes, the diversity of the antigen recognition repertoire is markedly decreased with age.

Advantages: Many immune-gerontologists have challenged negative interpretation of immunosenescence with respect to it's significance in ageing related alterations of the immune system. If one considers these changes from an evolutionary perspective, they can be viewed preferably as adaptive or remodeling rather than solely detrimental.

Whereas it is conceivable that global immune changes may lead to various diseases, it is also obvious that these changes may be needed for extended survival/longevity.