Beneficial effect of interferon-β treatment in patients with multiple sclerosis is associated with transient increase in serum IL-6 level in response to interferon-β injection

In order to predict the clinical benefit of interferon-β (IFN-β) to patients with multiple sclerosis (MS), the following markers were investigated; (1) chronological change of cytokines (IFN-γ, TNF-α, IL-6, IL-10, and TGF-β) after administration of IFN-β, (2) untoward effects of IFN-β such as headache and arthralgia, (3) backgrounds of the patients such as age and relapse rate, (4) efficacy of IFN-β therapy assessed by the change of relapse rate and progression of disability. Chronological blood sampling was performed 0, 10, and 24 h after injection of IFN-β. The increase of serum IL-6 level in response to IFN-β administration was associated with headache, arthralgia, relapse rate before treatment, and disability score at the initiation of the therapy. Significant association of change of serum TNF-α with age and headache was also observed. The important finding in this study was that patients with a transient increase in IL-6 in response to IFN-β showed a slow disease progression. This result suggests that this transient increase in the serum IL-6 predicts favorable response to IFN-β treatment.