Mechanisms of action of intravenous immune serum globulin in autoimmune and inflammatory diseases.

Intravenous immune serum globulin (IVIG) is primarily used as replacement therapy in patients with hypogammaglobulinemia. It has been over 15 years since IVIG was first shown to be effective in the treatment of patients with autoimmune thrombocytopenic purpura. Over the past decade, IVIG has been used in the treatment of a number of autoimmune and systemic inflammatory disorders. Although the use of IVIG in many of these immune-mediated disorders was purely speculative initially, we now have a much better understanding of the mechanisms by which IVIG exerts its effects in these autoimmune diseases. IVIG exhibits a number of immune modulatory activities that are mediated by the Fc portion of IgG through the Fc gamma receptor on a variety of cell types. Although the major component in IVIG is IgG, other minor components such as solubilized lymphocyte surface membrane determinants and specific antibodies to lymphocyte surface molecules may have important immunoregulatory effects on T- and B-cell immune responses. This review discusses the proposed mechanisms of action of IVIG in autoimmune and inflammatory disorders.