In tests on mice, they halted a rodent version of relapsing-remitting MS, the most common form of the serious autoimmune 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 symptoms ranging from numbness and tingling to full-blown paralysis.
Current treatments for MS rely on suppressing the immune system, which can make patients susceptible to infections and cancer.
Instead, the nanoparticle vaccine resets the immune system to stop the "friendly fire" attacks. The nanoparticles, made from two biodegradable compounds that occur naturally in the body, are attached to myelin proteins.
Injected into sick mice, the nanoparticles were viewed by the immune system as ordinary dying blood cells which can be ignored. This also caused the immune system to tolerate the myelin proteins attached to them.
Having learned to accept the proteins, the immune system also stopped attacking myelin-wrapped nerve fibres.
Study leader Professor Stephen Miller, from Northwestern University in Chicago, US, said: "We administered these particles to animals who have a disease very similar to relapsing-remitting multiple sclerosis and stopped it in its tracks. We prevented any future relapses for up to 100 days, which is the equivalent of several years in the life of an MS patient."
The research is reported in the journal Nature Biotechnology. Prof Miller's team is now adapting the nanoparticles to treat Type 1 diabetes and asthma.
"This is a highly significant breakthrough in translational immunotherapy," said the professor. "The beauty of this new technology is it can be used in many immune-related diseases. We simply change the antigen (protein) that's delivered."