Purification of Immunoglobulin G (IgG)

Several immunological procedures can be successfully carried out using nonpurified antibodies, such as unfractionated antisera, or ascitic fluid/culture supernatant containing monoclonal antibodies (MAbs). However, a much “cleaner” result can often be obtained if some form of enrichment or isolation of immunoglobulin is employed. Some procedures, such as conjugation with isotopes, fluorochromes, or enzymes, and preparation of immunoaffinity columns cannot usually be efficiently performed with nonpurified immunoglobulin, and some procedures may yield artifactual results if whole antiserum or ascitic fluid is used as a source of antibody. Purification of immunoglobulins is therefore essential or, at least, useful for a range of immunological methods. This process may consist of purification of total IgG or subpopulations (e.g., subclasses) of IgG from antisera/ascitic fluid/culture supernatant, or the isolation of a particular antigen binding fraction from such fluids. The former can be achieved by biochemical procedures, whereas the latter usually requires some form of affinity purification.