Neutralization of disease associated autoantibodies by an immunoglobulin M- and immunoglobulin A-enriched human intravenous immunoglobulin preparation

Immunoglobulin preparations enriched with IgM and IgA are used in the therapy of severe bacterial infections and for the treatment of acute graft- versus-host disease, but not as yet, in the treatment of autoimmune diseases. We investigated the potential of an IgM- and IgA-enriched immunoglobulin preparation to neutralize activity autoantibodies from patients with autoimmune diseases. We demonstrate that Pentaglobin® was at least as effective as intravenous immunoglobulin (Sandoglobulin®) in inhibiting autoantibody activity. Each of the immunoglobulin isotypes present in Pentaglobin® may be responsible for the inhibitory effect. Pentaglobin® immobilized on an affinity matrix retained the disease associated autoantibodies and interacted with F(ab')₂ fragments of IgG autoantibodies. Suppression of autoantibody activity is dependent, at least in part, on idiotypic interactions. The present findings provide a rationale for considering these preparations for the immunomodulation of autoimmune disease.