title: An In Vitro Diagnostic for Multiple Sclerosis Based on C-peptide Binding to Erythrocytes.
abstract: OBJECTIVE
  To investigate the utility of a blood-based lab test as an aid in identifying patients with Multiple Sclerosis (MS).
  
  
  METHODS
  Whole blood from subjects with MS, non-MS neurologic diseases, and healthy controls was centrifuged to isolate erythrocytes. Following the addition of exogenous C-peptide, the supernatant was assayed for remaining C-peptide using an enzyme linked immunosorbent assay (ELISA).
  
  
  RESULTS
  The cohort included subjects with MS (n=86), other non-MS neurologic diseases (OND n=75), and healthy controls (n=39). The average C-peptide bound to erythrocytes in MS samples (3.51±0.59pmol) was significantly higher than non-MS subjects (2.23±0.51pmol; p<0.001) and healthy controls (1.99±0.32pmol; p<0.001). Using a cutoff of 3.04pmol of C-peptide uptake, the test exhibited a sensitivity of 98.3% and specificity of 89.5%. A receiver-operator characteristic (ROC) curve generated from the ratio of the sensitivity to 1-selectivity resulted in an area under the curve of 0.97.
  
  
  CONCLUSIONS
  Exogenous C-peptide binding to erythrocytes has potential value in distinguishing MS subjects from non-MS neurologic diseases and healthy controls.
authors.affiliation: Department of Chemistry.
authors.forename: Sarah Y
authors.initials: SY
authors.lastname: Lockwood
authors.affiliation: Department of Chemistry.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Summers
authors.affiliation: Department of Neurology.
authors.forename: Eric
authors.initials: E
authors.lastname: Eggenberger
authors.affiliation: Department of Chemistry; Department of Cell & Molecular Biology. Electronic address: dspence@chemistry.msu.edu.
authors.forename: Dana M
authors.initials: DM
authors.lastname: Spence
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers; D002096:C-Peptide / Q000378:metabolism*; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000175:diagnosis* / Q000378:metabolism* / Q000628:therapy; D011485:Protein Binding; D012372:ROC Curve
chemical_list: D015415:Biomarkers; D002096:C-Peptide
keywords: C-peptide; Diagnostic; Erythrocytes; Multiple Sclerosis