Not every patient with inflammation of the brain and spinal cord has classical multiple sclerosis. Conditions such as MOGAD and NMOSD look similar but behave differently and respond to different drugs, which makes identifying the immune system's precise target clinically vital. A team led by Edgar Meinl at LMU's Biomedical Center, together with Simone Mader and partners in Vienna and at the LMU University Hospital, has now identified a previously unknown antigen in such patients.
The work began with a patient who had spinal cord inflammation but none of the known autoantibodies. The patient's blood antibodies bound to astrocytes, the support cells that surround blood vessels in the brain and spinal cord, and the target turned out to be MLC1, a protein on the astrocyte surface. A newly developed test then detected anti-MLC1 antibodies in 4 of around 300 patients diagnosed with MS or an MS-like disease.
Laboratory experiments showed that these antibodies destroy astrocytes and intensify spinal cord inflammation, evidence that they drive disease rather than merely marking it. Published in Science Translational Medicine, the findings expand the map of autoimmune attacks on the brain. With four medicines already approved for NMOSD in Germany, and recent trial evidence in MOGAD, recognising anti-MLC1 disease could help clinicians steer affected patients towards therapies that actually fit their condition.