Reducing Affinity in Immunoaffinity Chromatography

One of the advantages of writing a book is the process of doing the necessary research. The process of doing the necessary research always leads me to information that is new to me. Most of the time, this information is, to quote one of my former post-doctoral fellows, "obvious to the most casual observer." The most recent example comes from work for a forthcoming book on conformational analysis of biopharmaceutical products. I came across a paper by Recktenwald and colleagues (Recktenwald, A., Vernet, T., Storer, A.C., and Ziomek, E., Reduction of strong lipase-polyclonal antibodies binding by limited proteolysis, Anal.Biochem. 226, 31-34, 1995) at the Biotechnology Research Insititute at the National Research Council of Canada (Montreal). These investigatorsobserved what had confounded many of the early attempts to use polyclonal antibodies for immunoaffinity chromatography. Acknowledging that the use of monoclonal antibodies was preferable, these investigators showed that treatment of their polyclonal matrix with elastase or thermolysin markedly improved the yield of the immunoaffinity step; trypsin and subtilisin were less effective. This is consistent with the much earlier observations of Erickson and Neurath (Erickson, J.O. and Neurath, H., Antigenic properties of native and regenerated horse serum albumin, J.Exptl.Med. 78, 1-8, 1943) that treatment of antibody with trypsin reduced affinity but not specificity.

While there are several reasons such as specificity and reproducibility of supply to prefer the use of a monoclonal antibody for immunoaffinity purification, there are occasions where use of a polyclonal may be the only course available. This would appear to be a method which would permit the use of a polyclonal antibody for immunoaffinity chromatography.