Identification of antibodies as biological markers in serum from multiple sclerosis patients by immunoproteomic approach.

We identified the antibody against mitochondrial heat shock protein 70 (mtHSP70) in serum from multiple sclerosis (MS) patients by proteomics-based analysis. The prevalence of the anti-mtHSP70 antibody is significantly higher in serum from MS patients than in serum from Parkinson disease patients, multiple cerebral infarction patients, infectious meningoencephalitis patients, and healthy controls (HCs) (68% sensitivity; 74% specificity). We studied the clinical features and magnetic resonance imaging findings of MS patients with the anti-mtHSP70 antibody. As a result, there were no significant differences between the anti-mtHSP70-antibody-positive and -negative MS patients. Additionally, in our comprehensive analysis of the prevalence of both the anti-mtHSP70 antibody and the anti-phosphoglycerate mutase 1 (PGAM1) antibody, which was previously reported by us to also show a higher prevalence in serum from MS patients, the positivity rates of both these antibodies were significantly higher in serum from MS patients than in serum from patients with other neurological diseases and from HCs; moreover, the specificity of this combination assay was higher than that of the assay of only one antibody (57% sensitivity; 93% specificity). Results of our study suggest that not only the anti-PGAM1 antibody but also the anti-mtHSP70 antibody is good diagnostic markers of MS and the combination of both these antibodies is useful for a more specific diagnosis of MS.