Diminished production of type-I interferons and interleukin-2 in patients with multiple sclerosis

Several lines of evidence have supported the role of immunological mechanisms in the pathogenesis of multiple sclerosis (MS) and new immunomodulatory strategies for its treatment, e.g. subcutaneous application of interferon (IFN)-β, have emerged. We investigated the ability of peripheral blood mononuclear cells (PBMC) in 21 consecutive patients with clinically definite MS to produce interferons and lymphokines in response to viral or mitogenic stimulation. Ten patients showed clinical signs of disease activity (acute relapse) and 11 patients were in a stable condition. Additionally, white blood count, leukocyte differentiation and lymphocyte subtyping were performed. A group of age-related healthy blood donors served as control (n=20). There was no difference between patients and controls in the production of IFN-γ, tumor necrosis factor (TNF)-α and soluble interleukin (IL)-2 receptor. IFN-α and IFN-β responsiveness, however, was significantly lower in patients with stable disease than in patients with active disease and controls (p<0.001). Furthermore, secretion of IL-2 after stimulation was significantly diminished in both patient groups as compared to the control group (p<0.01). Analysis of T-cell subsets revealed a significantly lower amount of CD8(+) T-cells in patients with stable disease, leading to a significantly higher CD4/CD8 ratio in this group as compared to patients with active disease. Our study depicted an IL-2 deficiency in MS patients which is shared with other autoimmune diseases. In addition, our findings suggest that the ability to produce type-I IFNs, IFN-α and IFN-β, is primarily impaired in MS patients and changes in correlation to the course of disease activity.