On the role of aging in the etiology of autoimmunity

Several types of diseases, among others autoimmune illnesses, could be coupled with the general processes of aging. The two-edged sword of immune defense is directed on one side against environmental attacks and on the other against the body itself. However, one has to make a difference between normal (physiological) clearance and autoimmune diseases, although both sides of autoimmunity are influenced by the general processes of senescence. Aging of the thymus seems to be one of the key elements in the etiology of autoimmunity, although other cell types and their aging also play a substantial role in this process. Spontaneous genetic instability, acquired genetic mutations due to aging and the age-related alterations in the information level of the body may together be important elements in the pathomechanism of both physiological autoimmunity and autoimmune diseases. Nevertheless, physiological autoimmunity seems to be directed mostly by natural factors (such as aging and apoptosis) but primary autoimmune diseases may be caused by genetic instability that is enhanced by aging as well.