[The immune system in aging]

The immune system changes during life time. In this article we review which kinds of alterations take place. To exclude changes based on illnesses or chronical diseases, the SENIEUR protocol was performed, which defines "healthy elderly people". We focus on alterations in lymphocyte subsets, immunoglobulins and the cytokine network. Monocytes, eosinophils and basophils are without change during life, whereas the number of neutrophils and natural killer (NK) cells increase with aging. T- and B-lymphocytes are diminished in number as well as in function. The serum levels of immunoglobulins are mostly increased. The balance between TH1- and TH2-cells is disturbed and also TH1- and TH2-specific cytokines. Theses changes and their effects on the health status of the elderly are discussed in detail.