Researchers find possible cause for self-destructive immune system attacks in autoimmune diseases Autoimmune diseases, in which the body's own immune system attacks healthy tissue, can be life-threatening and can impact all organs. A research team at the Technical University of Munich (TUM) has now found a possible cause for these self-destructive immune system attacks: a hyperactive RANK protein on the surface of B cells. The research opens the door to new therapeutic possibilities. The immune system can be a mixed blessing: Usually it is highly effective in protecting the human organism against bacteria, viruses and mycosis and even cancer. But these defense cells can also turn against the body's own tissues and trigger autoimmune diseases, including for example rheumatoid arthritis and systemic lupus erythematosus, an illness involving chronic dermatitis and inflammation of the joints, the nervous system and internal organs or even become cancer cells themselves and develop into leukemias or lymphomas. But what causes these destructive immune system attacks?