The "nanoparticles" trick the immune system into behaving normally.
In tests on mice, they halted a rodent version of relapsing-remitting MS, the most common form of auto-immune disease.
Scientists believe the technology could be applied to a range of immune system disorders, including Type 1 diabetes, food allergies and asthma. MS occurs when the immune system attacks myelin, the fatty insulation that surrounds nerve fibres.
Breaks in the myelin coating prevent nerve messages being transmitted properly, leading to numbness, tingling and paralysis.
Professor Stephen Miller, from Northwestern University in Chicago, said: "This is a highly significant breakthrough in translational immunotherapy,"
The research appears in the journal Nature Biotechnology.