Isolation of bovine immunoglobulin G subclasses from milk, colostrum, and whey using immobilized egg yolk antibodies

Immunoaffinity columns were made with specific egg yolk immunoglobulin (Ig) Y against bovine IgG(1) and IgG(2) and were used to isolate pure IgG(1) and IgG(2) from Cheddar cheese whey or colostrum. About 10% of the IgY was specific for IgG, and 3% of the IgY was subclass-specific after hyperimmunization of laying hens with either IgG(1) or IgG(2). Up to 38% of the potential binding capacity of IgY was obtained after immobilization by reductive amination. The IgY columns were stable, and one column could be reused for more than 50 times for over a year with minimal loss in binding capacity. Milk that was free of either IgG subclass was successfully produced by the selective removal of IgG(1) or IgG(2) subclasses. Double-immunodiffusion analysis confirmed the isolation of subclasses from whey and colostrum and also confirmed that their removal from milk was specific.