Antibodies Against Sperm Associated Antigen 16 as a Novel Disease Marker for Multiple Sclerosis

Abstract

In multiple sclerosis (MS) research, there is a need for reliable and specific disease markers which could aid in disease diagnosis and prognosis prediction, as well as provide relevant information regarding underlying disease etiology and pathogenesis. We recently applied a phage cDNA display approach to identify antigenic targets interacting with antibodies present in the cerebrospinal fluid (CSF) of MS patients. A panel of 8 antigenic targets was identified with 86% specificity and 45% sensitivity for MS. The objective of this study was to characterize these novel antigen-antibody systems as biomarkers for MS. One of the novel identified antibody targets is sperm associated antigen 16 (SPAG 16). Recombinant SPAG16 protein was produced and a protein ELISA was optimised for high-throughput screening of CSF and serum samples from MS patients and controls. Besides being a valuable CSF marker, we demontrated anti-SPAG16 antibodies in the serum of 13% of MS patients with 100% specificity. Also, since little is known about the biological function of this protein, monoclonal antibodies against SPAG16 were produced and characterized by immunohistochemisty. Preliminary results show staining of cells in active chronic MS lesions. Future staining experiments will elucidate the expression pattern of the protein and its biological relevance in the MS disease process. In conclusion, application of autoantibody profiling in MS CSF led to the discovery of SPAG16 as an antibody target in MS. Detection of antibodies against this target antigen can aid in the diagnosis of MS patients an will provide valuable information regarding underlying MS disease processes.