Multiple sclerosis is a complex disease of the central nervous system (brain, spinal cord, and optic nerves) characterized by relapses (neurologic symptoms which appear rapidly but often improve over weeks or months), remissions and often progression of disability over time. MS is currently not a curable disease.  

MS is thought to be an immune-mediated disease, meaning that errors in the function of the immune system cause damage in the central nervous system. The immune system functions to protect the body from various environmental hazards or pathogens such as viruses, bacteria and fungi. The immune system is very sophisticated and has regulatory mechanisms in place that prevent it from recognizing body tissues as a pathogen.

In an immune-mediated disease such as MS, these regulatory mechanisms are disrupted and the ability to ignore itself is lost. In MS, the immune system recognizes tissue within the central nervous system as a pathogen and therefore causes inflammation and damage.