Interleukin-6 and oligoclonal IgG synthesis in children with acute disseminated encephalomyelitis

Interleukin-6 (IL-6) has a number of roles including recruitment of T lymphocytes and differentiation of B lymphocytes into IgG-secreting plasma cells. Furthermore, IL-6 is a neuropoietic cytokine with effects on neuronal differentiation, function and survival. We studied IL-6 concentrations in children with acute disseminated encephalomyelitis (ADEM; n = 14), and compared the values with those obtained from control patients with other inflammatory (OIND; n = 13) and non-inflammatory (NIND; n = 10) neurological disorders. Patients with ADEM had a significantly increased CSF IL-6 concentration compared with both OIND and NIND groups ( P < 0.01). Serum IL-6 was also increased in the ADEM group compared with the OIND group ( P < 0.05). CSF: serum IL-6 ratios were significantly increased in the ADEM group compared with the NIND group ( P < 0.05), suggesting an intrathecal production of IL-6 rather than its passive transfer across the blood-brain barrier alone. In ADEM, there was a significant correlation between an increased CSF IL-6 and an identical pattern of oligoclonal IgG synthesis in both serum and CSF ( P < 0.05). These results would suggest a role for IL-6 in the pathology of ADEM, and a possible direct link between an increased IL-6 and a proliferation of B lymphocytes with consequent IgG production.