The specific mechanism(s) by which TYSABRI exerts its effects in relapsing MS have not been fully defined.
TYSABRI is a monoclonal antibody that binds to α4-integrin—a known target in the pathogenesis of MS
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
CNS=central nervous system.