TYSABRI binds to α4-integrin, inhibiting the migration of lymphocytes into the CNS by retaining them in the periphery1
TYSABRI is believed to exert its efficacy by binding to the surfaces of lymphocytes and blocking their transmigration across the blood-brain barrier1
TYSABRI binds to the α4-subunit of α4β1 and α4β7 integrins expressed on the surface of all leukocytes exceptneutrophils, and inhibits the α4-mediated adhesion of leukocytes to their counter-receptor(s)1
The specific mechanism(s) by which TYSABRI exerts its effects in relapsing MS have not been fully defined.
In demyelinating diseases such as MS, evidence suggests α4-integrin may play a key role in inhibiting CNS migration of lymphocytes—a trigger in the inflammatory process in MS1,2
TYSABRI is a monoclonal antibody that binds to α4-integrin—a known target in the pathogenesis of MS
The α4 subunit α4β1 integrin is expressed on the surface of all leukocytes (except neutrophils)
TYSABRI may exert its effects by blocking the interaction of α4-integrin with adhesion molecules on the vascular endothelium
This may prevent the migration of leukocytes across the blood-brain barrier, inhibiting further recruitment and inflammatory activity of activated immune cells
TYSABRI may further act to inhibit the interaction of α4-expressing leukocytes with their ligands in the extracellular matrix and on parenchymal cells, thereby inhibiting further recruitment and inflammatory activity of activated immune cells