Summary

Backgraound: Intravenous immunoglobulin administration has been beneficially used for the treatment of a variety of autoimmune diseases including myasthenia gravis, although its mode of action and active components have not yet been fully identified.
Objectives: To isolate from IVIg[1] a disease-specific fraction involved in the therapeutic activity in myasthenia and to identify its properties and function.
Results: IVIg administration in experimental autoimmune MG[2] results in suppression of disease that is accompanied by decreased Th1 cell and B cell proliferation. Chromatography of IVIg on columns of IgG from rats with EAMG[3] or from MG patients resulted in depletion of the suppressive activity that IVIg has on rat EAMG. Moreover, the minute amounts of IgG fractions eluted from the EAMG or MG-specific columns retained the immunosuppressive activity of IVIg.
Conclusions: Our study supports the notion that the therapeutic effect of IVIg is mediated by a minor disease-specific immunoglobulin fraction that is present in IVIg and is essential for its therapeutic activity.