Introduction to Secondary Antibodies
Secondary antibodies bind to the unconjugated primary antibody to detect the antigen that the primary antibody is bound to. These antibodies are usually purified using an antigen affinity purification system where the antigen attached to the chromatography matrix is an immunoglobulin of the same Ig class as the primary antibody. Sometimes a secondary antibody, which is actually polyclonal in nature, must be absorbed by additional chromatography techniques to remove potential cross reactivity to other antibodies or serum proteins from other animal species. This can be an advantage to using the indirect secondary antibody system to detect primary antibodies because a signal amplification occurs when multiple secondary antibodies bind to a single primary antibody.