Large-scale purification of IgM from human sera. Comparison of three optimized procedures utilizing protein A chromatography.

for the preparation of gram amounts of IgM from human sera sedimentation at 100,000 g or treatment with ZnSO4 of the redissolved "euglobulin"-precipitate was compared to direct precipitation from the clarified serum by boric acid. Three alternative large scale purification procedures were developed, leading to an IgM-sample characterized as pure by various criteria. Inclusion of protein A chromatography proved to enhance the yield very considerably.