Immunoglobulin (IgG) therapy is a strategy for treatment of autoimmune, immunodeficiency and acute infectious diseases. Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare and refractory autoimmune disorder of the peripheral nervous system, characterized by symmetric weakness, impaired sensation and damaged myelin (demyelination). Although intravenous immunoglobulin (IVIg) preparation is used for the therapy, the mechanism of this therapy on demyelination has not been understood. In this study, we examined the effect of human IgG on the lysolecithin-induced demyelination in the mouse sciatic nerve.
Lysolecithin was injected into sciatic nerves of the ICR mice (day 0) to induce demyelination and 20 mg (i.v., day 1) and 10 mg (i.p., day 3) of IVIg preparation or the same volumes of saline for control group were administered. Demyelination area and infiltrated macrophages were evaluated with the longitudinal sciatic nerve sections on the day 7 and 14 by immunostaining. The demyelination areas of the IVIg-treated group were significantly less than those of the control group. CD68⁺ macrophages infiltrated in the lesions and CD68⁺ CD206⁺ macrophages were more prominent in IVIg-treated group.
The results suggest that IgG therapy decreased demyelination areas possibly through the accumulation of M2-type macrophages.