Isoantibodies in immunoglobulin for intravenous use may cause erythrocyte sequestration

Background and Objectives: IVIg, while generally a safe therapy for a varie ty of immunological disorders, can have detrimental effects on erythrocyte (RBC) homeostasis. We studied the mediation of erythrophagocytosis by isoan tibodies in IVIg, Materials and Methods: RBC were exposed to IVIg and bindi ng of IgG determined by flow cytometry, In vitro phagocytosis of these RBC was assayed, Results: Anti-A and anti-B in IVIg mediate fc-dependent erythr ophagocytosis even in the presence of excess IVIg, Removal of these isoanti bodies from IVIg prevents IgG binding and erythrophagocytosis. Complement e nhances IVI mediate RBC sequestration. Conclusion: It may be desirable to r emove isoantibodies from IVIg especially for anemic patients or those who r espond to the IVIg with a hemolytic episode.