IL6 and systemic lupus erythematosus: Finally, we only measured analytes in serum and did not assess their levels in CSF, and a previous work that included 30 SLE patients with CNS NPSLE, yet no CI, showed that for some analytes (including IL-6, IL-10, IFN-γ, and TNFα) the serum levels did not correlate with the CSF levels (49), therefore it remains possible that some of the measured analytes are produced locally in the brain and that their elevated levels are not reflected in the circulation.