Increased Intrathecal High-Avidity Anti-Tau Antibodies in Patients with Multiple Sclerosis

BACKGROUND Antibodies against tau protein indicate an interaction between the immune system and the neurocytoskeleton and therefore may reflect axonal injury in multiple sclerosis (MS). METHODOLOGY/PRINCIPAL FINDINGS The levels and avidities of anti-tau IgG antibodies were measured using ELISA in paired cerebrospinal fluid (CSF) and serum samples obtained from 49 MS patients and 47 controls. Anti-tau antibodies were significantly elevated intrathecally (p<0.0001) in the MS group. The CSF anti-tau antibody levels were lower in MS patients receiving therapy than those without treatment (p<0.05). The avidities of anti-tau antibodies were higher in the CSF than in the serum (MS group p<0.0001; controls p<0.005). Anti-tau avidities in the CSF were elevated in MS patients in comparison with controls (p<0.05), but not in serum. CONCLUSIONS MS patients have higher levels of intrathecal anti-tau antibodies. Anti-tau antibodies have different avidities in different compartments with the highest values in the CSF of MS patients.