The blood-brain barrier is a tightly packed layer of cells (called endothelial cells) that line the blood vessels in the brain and spinal cord. This barrier prevents large molecules, immune cells, and disease-causing organisms (eg viruses) from passing from the blood stream into the central nervous system (brain and spinal cord).
In multiple sclerosis, the blood-brain barrier is damaged or weakened in some way and immune cells are able to cross. These cells attack the myelin around nerves, which leads to MS symptoms.
One of the disease modifying drugs, natalizumab (Tysabri), is thought to act by stopping immune cells from passing through the blood-brain barrier.
Last updated: November 2017
Last reviewed: January 2016
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- Neurobiology Of Disease 2015;74:14-24. Summary Focal disturbances in the blood-brain barrier are associated with formation of neuroinflammatory lesions.
- Archives Of Medical Research 2014;45(8):687-697. Summary Role of the blood-brain barrier in multiple sclerosis.
- FEBS Letters 2011;585(23):3770-3780. Summary How do immune cells overcome the blood-brain barrier in multiple sclerosis?