IL-6 increase in CSF as additional diagnostic criteria for definite neuro-behcet disease

Background: When the central nervous system (CNS) is the primary affected site in an initial attack of Behcet’s disease (BD), the differential diagnosis is particularly challenging. Some cases remain unclassified or qualified as probable Neuro-Behçet disease (NBD). Moreover, it was demonstrated that cytokines play a crucial role in the pathogenesis of NBD. We therefore studied peripheral and cerebrospinal inflammatory profile of these patients. Methods: Twenty two parenchymal NBD patients diagnosed according to the international consensus recommendation criteria and classified into definite (d-NBD; n= 13) and probable (p-NBD ; n=9) were sampled at their first neurological symptoms and compared with healthy control subjects (n=10). Oligoclonal bands of IgG were detected by isoelectric focusing on agarose and immunoblotting of matched serum and Cerebrospinal fluid (CSF) sample pairs. Cytokines and transcription factors related to TH1, TH2, TH17 and T regulatory populations were studied by quantitative RT-PCR in the CSF. Results: Oligoclonal bands (OCB) were present in only 1/22 patients. Two d-NBD patients had OCB in the CSF showing pattern 4. In NBD CSF samples, INF gamma, IL-17 and IL-10 expressions were significantly elevated compared with controls, however no difference in those cytokine expressions was observed between d-NBD compared to p-NBD. The most stricking finding was the significant increase of CSF IL-6 in d-NBD compared to p-NBD. Conclusion:These results indicate the rare presence of OCB in parenchymal NBD patients. Additionally, CSF IL-6 could help us to identify definite NBD. Keywords: Behçet’s disease, central nervous system, cerebrospinal fluid, cytokine.