Clinical uses of intravenous immune globulin: immunoglobulin replacement therapy and treatment of autoimmune cytopenias.

Intravenous immune globulin (IVIG) is indicated for IgG replacement in antibody deficiency syndromes and as immunoregulatory therapy in some autoimmune diseases. Two case histories illustrate both aspects of IVIG therapy. 1. Patient 1 is a 24-year-old male with agammaglobulinemia. He was successively treated with monthly IMIG, paternal plasma, and then over the last 5 years, IVIG. On IgG doses of 250 mg/kg q/4 weeks, IgG trough levels remained below 200 mg IgG/dl. IgG half-life was reduced. Although asymptomatic for prolonged periods of time, he eventually developed clinically evident inflammatory bowel disease. Optimal IVIG replacement therapy requires normal IgG half-life and adequate IgG trough levels. 2. Patient 2 is a 12-year-old girl with autoimmune neutropenia, recurrent skin infections, and ileitis unresponsive to antibiotics and to steroid therapy. IVIG at a dose of 3,000 mg/IgG/kg over 3 days significantly increased her neutrophil count. Subsequently, she has required 1,000 mg/kg of IVIG q/4 weeks for maintenance. Antineutrophil autoantibodies have persisted. There is synergism of IVIG with high doses of corticosteroids. The mechanism of action of IVIG seems to involve a blockage of the RES system. IVIG therapy is safe even at high doses for most patients. However, anaphylactic reactions have been observed in IgA-deficient patients with IgE anti-IgA antibodies. The full spectrum of therapeutic applications of IVIG is still being explored. For some patients self-infusion of IVIG at home is an appealing treatment alternative.