Autoimmune diseases affect several 100 million people world wide and is a tremendous public health problem comparable with heart disease and cancer. We have focused our research to a group of severe autoimmune diseases, called ANCA (anti-neutrophil cytoplasmic antibody) associated systemic vasculitis. The diseases present with acute inflammation in the small vessels and cause rapidly progressive renal failure and life threatening lung bleedings if left untreated. Delay in treatment can rapidly lead to deterioration of vital organ function, while institution of toxic immunosuppressive therapy for patients with, for instance infections, may have detrimental effects. The mixture of clinical and pre-clinical researchers makes it possible to address clinically relevant questions on a molecular level. The work is focused on deciphering the underlying disease biology and translate this into new concepts of treatment as well as development of new diagnostics.