Preparation of human immunoglobulin by ammonium sulfate precipitation.

Crude IgG precipitated from plasma by the addition of an equal volume of 4 M ammonium sulfate was fractionated on DEAE-cellulose column to obtain pure IgG as shown by disc electrophoresis, immunoelectrophoresis and gel filtration. The processed IgG was free of plasmin and plasminogen and did not undergo fragmentation or aggregation on storage at 40 degrees C for at least 4 weeks. The anticomplement activity was low and the antibody activity was retained.