Isolation of Human IgA Utilizing Protein a Affinity Chromatography

Human serum IgA was isolated employing a system of G-200 column chromatography, anion exchange (DE-52) chromatography, and passage over protein A and anti-IgG Sepharose 4B columns. Polyacrylamide gel electrophoresis (PAGE) analysis of the isolated immunoglobulin revealed polypeptides corresponding to alpha and light immunoglobulin chains of IgA which were identified immunochemically as IgA. Ultracentrifugation studies revealed that the isolated immunoglobulin co-migrated with 7S IgG markers. This procedure may serve as an alternative to classical isolation procedures of IgA from human serum.