Induction of systemic TNFalpha in natalizumab-treated multiple sclerosis.

The mRNA expression of eight different cytokines in peripheral blood mononuclear cells in 19 individuals with multiple sclerosis was determined at baseline and after 6 months of open-label treatment with natalizumab. Cellular expression of tumor necrosis factor alpha (TNFalpha) mRNA and number of cells secreting TNFalpha and interferon gamma protein significantly increased over the 6 months. Kurtzke EDSS scores improved because of the resolution of relapses, but not fatigue severity scores. The observed increases in systemic proinflammatory cytokines by natalizumab treatment are discussed in relation to fatigue and systemic immunity.