Immune function, autoimmunity, and selective immunoprophylaxis in the aged

Many changes occur in the immune system with age. The involution of the thymus plays a major role in immune senescence. Related to this event are the altered ratio of helper to suppressor T-lymphocyte subsets, decrease in immune response by both cell-mediated and humoral branches of the immune system, and increase in autoimmune activity. The clinical implications of these changes are the elderly person's increased susceptibility to infections such as pneumococcal pneumonia, influenza A, and tetanus as well as increased autoimmune activity, reflected by pernicious anemia. Other changes may be increased susceptibility to neoplasms and perhaps acceleration of the aging process. A high index of suspicion should be present for the diagnosis of pernicious anemia in the elderly population. Knowledge of the many autoantibodies that might be present without illness is important when evaluating for disease processes. The relationship of the senescent immune system to the aging process is still unknown. Investigations of this matter, as well as of the function of immune system components and their relationship to disease processes, are continuing. Most methods proposed for enhancing the immune system are still experimental. However, immunizations have been proved to be an effective means of reducing morbidity and mortality from certain infectious diseases in the elderly. Therefore, it is strongly recommended that all elderly persons who are at risk for pneumococcal pneumonia, influenza, and tetanus receive the proper immunizations.