Purification of Human Serum γ-Globulin for Immunologic Studies: γ-Globulin Fragmentation after Sulfate Precipitation and Prolonged Dialysis

Abstract

Summary Diethylaminoethyl (DEAE)-cellulose chromatography of whole human serum, and sodium sulfate precipitated serum globulins in Trisphosphate at pH 8.6, 0.005 M phosphate was used to obtain highly purified human γ-globulins. A 14-fold increase in yield of purified γ-globulin was obtained for a given column size when sodium sulfate precipitated globulins were used. γ-Globulins so derived were incorporated in Freund's adjuvant and injected repeatedly into rabbits over many months. The hyperimmune rabbit serum contained antibodies directed solely against the γ-globulins of human serum and cross-reactive with β2A and β2M globulins when tested by immunodiffusion techniques. Sustained immunization in several animals has been stressed as a more critical procedure for assessing purity of a γ-globulin preparation than initial in vitro immunodiffusion studies. The use and merits of specific and potent anti-human γ-globulin serums in the preparation of immunohistologic reagents has been discussed. Chromatographically prepared γ-globulins have been studied by immunodiffusion, electrophoretic and analytical ultracentrifugal techniques. Fragmentation was found repeatedly in preparations derived from sodium sulfate precipitated globulins which had been allowed to dialyze under sterile conditions for long periods against the chromatography buffer. The fragmentation is presumably different from the produced by papain because both electrophoretically slow and fast fragments retained the ability to bind antigens.