IL-6 detection in multiple sclerosis brain.

By using a double-label immunohistochemistry technique, we demonstrated the presence of interleukin-6 (IL-6) in acute and chronic active plaques from the brain of six patients with multiple sclerosis (MS). IL-6 was mainly associated with astrocytes and rarely with macrophages or mononuclear infiltrating cells. The pattern of distribution for IL-6 immunoreactivity was similar to that of HLA-DR expression, but the two molecules almost never colocalized on the same cell. Our data indicate that in MS central nervous system IL-6 is predominantly located within resident glial cells which are concentrated at the sites of ongoing demyelination and immune activation. Although IL-6 exhibits several proinflammatory activities, indirect evidence suggests that the cytokine may also play an immunomodulatory role in inflammatory demyelinating disorders.