Interleukin 17 alone is not a discriminant biomarker in early demyelinating spectrum disorders

Background: Radiologically isolated syndrome (RIS) is a sub clinical demyelinating neurological disorder and to date no biomarker that triggers the seminal event has been identified. As for multiple sclerosis (MS), disease activity and clinical course are unpredictable. In MS, exploratory studies reported increased IL-17 levels in CSF but results in detecting IL-17 in serum at different stage of the disease are controversial.

Objectives: We investigate levels of IL-17 in serum and CSF in patients diagnosed at different stages of demyelinating diseases (RIS, CIS, relapsing remitting (RR) or active multiple sclerosis patients:AMS) as a marker of inflammatory condition.

Methods: 1417 sera has been tested for IL-17A (1177 from active MS, 80 RRMS, 35 RIS, 35 CIS, 10 IIH: idiopathic intracranial hypertension, and 80 controls) and 240 CSF from RIS, CIS, IIH and controls.

Results: No difference has been found between RIS who early clinically converted and CIS patients who rapidly evolve in McDonald or clinically definite MS, nor active MS. No correlation was found with usual MRI or CSF criteria.

Conclusion: Our results do not confirm that IL-17 can be considerate as a reliable marker of inflammation in the demyelinating spectrum disorders, either in blood or CSF.