Differential Diagnostics of Active Progressing Multiple Sclerosis Using a Fluorescent Biomarker with Resonance Energy Transfer

: Previous data showed that myelin-reactive autoantibodies found in patients with multiple sclerosis and mice with experimental autoimmune encephalomyelitis recognize and hydrolyze various fragments of myelin basic protein (MBP). Moreover, antibody-mediated cleavage of the encephalithogenic fragment MBP81-103 flanked with two fluorescent proteins can serve as a new biomarker of multiple sclerosis. Here we describe creation of the next generation of this biomarker based on antibody-dependent degradation of a new chemically synthesized fluorescent substrate with resonance energy transfer that contains fluorophore Cy5 and quencher QXL680 separated by MBP81-99 protein (Cy5-MBP81-99-QXL680). This substrate is degraded during incubation with purified antibodies and B cells from patients with multiple sclerosis, but not healthy volunteers.