CD134 plays a crucial role in the pathogenesis of EAE and is upregulated in the CNS of patients with multiple sclerosis.

We investigated the role of the CD134 (also named OX40) molecule in experimental allergic encephalomyelitis (EAE) and multiple sclerosis (MS). We examined the susceptibility of Cd134(-/-) mice to EAE, an autoimmune murine model that is dependent on infiltrating CD4+ T lymphocytes reactive to myelin proteins. EAE induced by myelin oligodendrocyte glycoprotein (MOG) injection in Cd134(-/-) mice showed less severe clinical signs of disease and markedly reduced inflammatory infiltrates within the central nervous system (CNS). Resistance was associated with a strong reduction of pathogenic IFNgamma-producing T cells infiltrating the CNS of Cd134(-/-) mice. Furthermore, analysis of CNS tissue sections from EAE animals and MS patients revealed the presence of CD134+ cells that were localized in active lesions, mainly in perivascular infiltrates. The presence of CD134-expressing T cells in brain tissue of MS patients and EAE affected mice, together with the functional evidence provided by the significant decrease in disease score obtained in Cd134(-/-) mice, indicate that interfering with the CD134 molecule in T cells may be an appropriate target for therapeutic intervention in active MS.