[Aging of the immune system]

With increasing age a rise in the incidence of infections, inflammatory diseases such as arteriosclerosis and tumors and simultaneously a reduction in the success of vaccinations can be observed. A dysfunctional immune system is responsible for this. The immune system can be divided into three domains. The first barrier, the epithelioid protective barrier of the skin and the mucosa, loses its protective function with age. The second barrier, the innate immune system, is characterized in old age by chronic low-grade inflammation and a simultaneous reduction of an adequate response to pathogens. The reduced hematopoiesis of new naïve lymphocytes and a reduction of diversity describe the adaptive immune system, the third barrier at old age. These changes, summarized as immunosenescence, are partly responsible for many degenerative diseases.