Tysabri is a medication used to treat both Crohn’s disease and different forms of Multiple Sclerosis (MS). such as clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease in adults. 

Both autoimmune diseases are caused by immune cells attacking healthy cells in the body that are misrecognized as foreign cells that need to be destroyed.  

MS is an autoimmune disorder of the central nervous system characterized by inflammation, demyelination of nerve fibers in your brain and spinal cord, as well as the optic nerves, and axonal loss.  MS lesions are thought to occur when immune cells cross the blood brain barrier and damage healthy tissues. 

As these healthy tissues such as nerves and myelin sheathing continue to be damaged,  it can lead to a decrease in mobility and affect cognitive function. 

Tysabri is thought to work by helping prevent harmful immune cells from crossing into the central nervous system. Reducing the harmful immune cells in the brain may help reduce damage and inflammation caused by MS. 

For Crohn’s disease, the healthy cells that line the GI tract are attacked. This causes tissue inflammation, breakdown, and the formation of ulcers. Tysabri works by binding to the surface of white blood cells so they cannot pass through tissue layers and cause inflammation.