Researchers are a step closer to finding an explanation for autoimmune diseases – i.e. diseases in which our own immune system damages the body. With the help of a new technique, researchers from Aarhus University have succeeded in identifying the particles in the blood that determine the development of autoimmune diseases. They have discovered that patients with the autoimmune disease Systemic Lupus Erythematosus (also called SLE or Lupus) form a previously unknown type of protein particle in the blood and that this particle is so large, it finds its way into the vascular wall, where it causes damage. The disease is potentially life-threatening and can, for example, cause blood clots and inflammation of the joints and organs. “We can see that the patients have an elevated proportion of the large particles in the blood. Because of their size, these are distributed right at the edge of the blood vessel, where they can potentially end up in the vessel wall and create inflammation,” explains postdoc Kristian Juul-Madsen from the Department of Biomedicine at Aarhus University. Early diagnosis of the disease is important because treatment can reduce symptoms and prevent organ damage. It is also interesting in a clinical context for researchers to be able to take a blood sample and five minutes later have an answer as to whether the patient is on the way to developing Lupus or is already ill.