Antibodies specific for metal-chelate conjugates: Generation and use of recombinant libraries and applications to cancer epidemiology
Description
Antibodies to metal-chelate complexes have potential applications in biotechnology, medicine, and environmental analyses. This report details a progression of studies from work with a previously isolated monoclonal antibody, to the isolation of a recombinant antibody from a semi-synthetic scFv library and finally to the production of an immune library and the subsequent isolation and characterization of an scFv from that immune library. A monoclonal antibody was used to detect levels of cadmium in the serum of pancreatic cancer patients and non-cancer controls. It has been suggested that exposure to cadmium is associated with the development of pancreatic cancer. Our studies have demonstrated that patients with pancreatic cancer had a significantly higher concentration of serum cadmium than non-cancer controls. An scFv specific for Cd(II)-EDTA was isolated from a human semi-synthetic phage display library and subsequently characterized. While this particular antibody is not therapeutically useful because of its low affinity, the techniques developed in this study could be employed with an alternate library or in search of other metal-chelate complexes. While many researchers prefer naive libraries because of their diversity and the ability to pan the library for many targets; an immune library, synthesized from animals immunized with specific metal-chelate complexes may yield a greater number of specific, higher-affinity antibodies to our targets of interest. Phage-display libraries produced from an immunized source are inclined to include variable genes specific for the immunized antigen(s), many of which are already affinity matured. An scFv specific for UO2 2+-DCP was isolated from the combined sheep and rabbit immune phage display library. This scFv showed a marked increase in affinity for its antigen over the scFv isolated from the semi-synthetic library. While the binding affinity of the scFv for its antigen was not as high as monoclonal antibodies previously isolated against this antigen, the beauty of recombinant antibodies allows for the potential manipulation and maturation of the antibody's binding affinity which may drastically improve and perhaps surpass that of the monoclonal antibodies. This combination of studies demonstrates the great potential of recombinant antibody technology and the wide variety of uses for antibodies that bind to metal-chelate complexes