An In Vitro Diagnostic for Multiple Sclerosis Based on C-peptide Binding to Erythrocytes.

Abstract

To investigate the utility of a blood-based lab test as an aid in identifying patients with Multiple Sclerosis (MS). 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). 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. Exogenous C-peptide binding to erythrocytes has potential value in distinguishing MS subjects from non-MS neurologic diseases and healthy controls.