The cerebrospinal fluid CD4/CD8 ratio and interleukin-6 and -10 levels in neurosarcoidosis: a multicenter, pragmatic, comparative study

BACKGROUND AND PURPOSE: Neurosarcoidosis is a rare inflammatory disorder of unknown cause. The aim of this study was to evaluate the value of T/B lymphocyte population counts and the concentrations of the cytokines interleukin (IL) 6 and IL‐10 in the cerebrospinal fluid (CSF) of neurosarcoidosis patients. METHODS: A retrospective study CSF biomarkers was conducted in patients with neurosarcoidosis who underwent CSF analysis between 2012 and 2017 as well as various control populations. RESULTS: Forty‐three patients with neurosarcoidosis, 14 with multiple sclerosis (MS) and 48 with other inflammatory disorders were analyzed. The CSF IL‐6 levels were higher in sarcoidosis patients than in MS patients (median 8 vs. 3 pg/ml, P = 0.006). The CSF CD4/CD8 ratio was higher in sarcoidosis patients than in MS patients and in patients with other inflammatory disorders (median 3.18 vs. 2.36 and 2.10, respectively, P = 0.008). The CSF IL‐6 level was higher in patients with active neurosarcoidosis than in non‐active neurosarcoidosis patients (median 13 vs. 3 pg/ml, P = 0.0005). In patients with neurosarcoidosis, a CSF IL‐6 concentration >50 pg/ml was associated with a higher risk of relapse or progression‐free survival (hazard ratio 3.60; 95% confidence interval 1.78‐23.14). A refractory neurosarcoidosis patient was treated with an anti‐IL‐6 monoclonal antibody that produced a complete neurological response. CONCLUSIONS: The CSF CD4/CD8 ratio and IL‐6 concentration are increased in neurosarcoidosis compared to MS and other inflammatory disorders. A CSF IL‐6 concentration >50 pg/ml is associated with relapse or progression of neurosarcoidosis. IL‐10 levels may be elevated in neurosarcoidosis.