Southwestern Internal Medicine Conference: high-dose intravenous gamma globulin therapy: how does it work?

In the past, IgG replacement has been used primarily to treat patients with hypoglobulinemia or agammaglobulinemia. With the availability of preparations of IgG suitable for intravenous use (IVIG), much higher doses may now be given safely. Surprisingly, administration of very high doses of IVIG in several immunologically related diseases have produced improvement not achieved by other means of therapy. The mechanisms by which IVIG causes these diseases to improve vary with the immunopathogenesis of each disease. Provision of antibodies otherwise unavailable to a given patient, IgG-Fc-receptor blockade, modification of complement activation and modulation of the immune response by anti-idiotypic antibodies are discussed as mechanisms of action of IVIG. Because of the expense and relative scarcity of large amounts of purified, pooled normal IgG, this form of therapy should be used only for selected illnesses for which other treatment is ineffective.