Switch-associated protein 70 antibodies in multiple sclerosis: relationship between increased serum levels and clinical relapse

Objective To identify an antibody biomarker for multiple sclerosis (MS) that can be used as a predictor of MS relapses. Methods MS patients’ sera were screened by a protein macroarray derived from human fetal brain cDNA library (hEX1). Sera of 90 consecutive relapsing remitting MS (RRMS) patients and age-matched 145 Behçet’s disease (BD) patients, 40 infectious meningoencephalitis patients, and 70 healthy controls were screened by ELISA for serum antibodies against the selected clone. Results Sequencing of the clone with the highest signal intensity revealed switch-associated protein 70 (SWAP70) as a potential target autoantigen in RRMS. ELISA studies showed high-titer SWAP70-antibodies in 21 (23.3 %) RRMS and 7 (4.8 %) BD patients. SWAP70 antibodies were more likely to be found positive in sera obtained during or shortly after a relapse. Conclusion Detection of SWAP70 antibodies during the attack period might suggest that SWAP70 is involved in MS relapse pathogenesis. Whether serum SWAP70 antibody detection may be utilized as an MS relapse predictor should be tested in prospective studies.