Systemic lupus erythematosus (SLE) is a severe chronic inflammatory autoimmune disease that may affect different organs of the body. It is considered a connective tissue and blood vessel disease. In SLE, the immune system regards and fights the body's own tissue as alien for some unknown reason, whereby tissue-damaging centers of inflammation may arise in various areas of the organism.
 
5 to 10 new cases of SLE are diagnosed for every 100,000 inhabitants annually. Women are generally afflicted ten times as often as men. SLE usually appears in young women between the ages of 25 and 30. People of African, Indian or Asian origin contract SLE more frequently than other ethnic groups.
  
What causes SLE and for what reason is still largely unknown. Genetic factors seem to play a significant role apart from sex. Several studies? confirm that there is not just a single cause for SLE but that various factors interact in the disease's origin. 
 
SLE is an autoimmune disease. This means that the human defense (immune) mechanism, which is supposed to combat pathogens such as bacteria, viruses and fungi, attacks its own tissue.
 
What causes the immune system's erroneous programming and why the defense mechanism can no longer distinguish between "self" and "foreign" is not yet known in detail. However, this much is clear: several erroneous and uncontrolled simultaneous immune reactions occur in SLE patients.