Effective biomarkers for multiple sclerosis diagnosis, assessment of prognosis, and treatment responses, in particular those measurable in blood, are largely lacking. We have investigated a broad set of protein biomarkers in cerebrospinal fluid (CSF) and plasma using a highly sensitive proteomic immunoassay. Cases from two independent cohorts were compared with healthy controls and patients with other neurological diseases. We identified and replicated 10 cerebrospinal fluid proteins including IL-12B, CD5, MIP-1a, and CXCL9 which had a combined diagnostic efficacy similar to immunoglobulin G (IgG) index and neurofilament light chain (area under the curve [AUC] = 0.95). Two plasma proteins, OSM and HGF, were also associated with multiple sclerosis in comparison to healthy controls. Sensitivity and specificity of combined CSF and plasma markers for multiple sclerosis were 85.7% and 73.5%, respectively. In the discovery cohort, eotaxin-1 (CCL11) was associated with disease duration particularly in patients who had secondary progressive disease (PCSF< 4 × 10−5,Pplasma< 4 × 10−5), and plasma CCL20 was associated with disease severity (P= 4 × 10−5), although both require further validation. Treatment with natalizumab and fingolimod showed different compartmental changes in protein levels of CSF and peripheral blood, respectively, including many disease-associated markers (e.g., IL12B, CD5) showing potential application for both diagnosing disease and monitoring treatment efficacy. We report a number of multiple sclerosis biomarkers in CSF and plasma for early disease detection and potential indicators for disease activity. Of particular importance is the set of markers discovered in blood, where validated biomarkers are lacking.

Backgound: Differential diagnosis of multiple sclerosis (MS) includes a variety of disorders and misdiagnosis is common. Objective: To follow-up persons with suspected onset of MS but in whom the diagnostic investigation was negative. Methods: In a prospective study including 271 persons with clinical features of suspected MS onset, 136 persons were diagnosed with MS or clinically isolated syndrome (PwMS), 46 had other disorders, and 89 persons had a negative diagnostic work-up, i.e. persons with undetermined diagnosis (PwUD). They underwent diagnostic reassessment, and those who remained without a diagnosis were investigated for signs of pathology including cognitive tests and assessments of quality of life (QoL). Results were compared with those of PwMS and 24 age and sex matched healthy controls (HC). Results: After reassement 55 (20%) persons still had undetermined diagnosis (PwUD). They had similar age and gender distribution as PwMS. In 76% of PwUD, the suspected clinical onset included sensory symptoms. PwUD and PwMS scored similarly in cognitive tests and QoL but significantly lower than HC. At 3 years follow-up, PwMS and PwUD improved in most test parameters, but PwUD scored lower than PwMS in cognition. Conclusion: PwUD constituted the dominating differential diagnosis in persons with suspected clinical onset of MS. QoL and cognition were comparable with those of PwMS but significantly lower than in HC.

Background Elevated levels of the cerebrospinal fluid (CSF) neuronal injury markers (neurofilament light chain [NF‐L] and total tau protein [t‐tau]) and of the astroglial marker glial fibrillary acidic protein (GFAP) are found in etiologically different neurological disorders affecting the peripheral and the central nervous system. Aims To explore the role of CSF biomarkers in the clinical management of patients admitted for alarming neurological symptoms, but in whom neurological disorders could be excluded. Methods Study participants were patients seeking medical attention for neurological symptoms primarily considered to be caused by a neurological diagnosis and investigated according to clinical routine. Demographic, clinical, and CSF data were extracted retrospectively from medical records. Patients with a final neurological diagnosis were excluded. Results Out of 990 patients, 900 with a neurological diagnosis were excluded leaving 90 patients without a final neurological diagnosis. Sixty‐eight (75.6%) were females. Median (range) age at lumbar puncture was 34.7 (16.9‐65.1) years. Age‐adjusted CSF‐NF‐L, CSF‐t‐tau, and CSF‐GFAP concentrations were normal in 89 (98.9%), 86 (95.6%), and 87 (96.7%) patients, respectively. Conclusion In patients with significant neurological symptoms but in whom a neurological diagnosis could not be made, the CSF markers NF‐L, t‐tau, and GFAP did not indicate signs of neuronal or astroglial cell damage close to symptom onset. Consequently, increased levels of CSF markers are not expected in this patient group and, if present, should raise suspicion of underlying neurological disorders and motivate further investigations.