Polyclonal antibodies from patients immunized with a globe H-keyhole limpet hemocyanin vaccine: Isolation, quantification, and characterization of immune responses by using totally synthetic immobilized tumor antigens

We have previously reported on a carbohydrate-based vaccine program for imm unotherapy in cancer patients. One such vaccine, based on the globe H antig en conjugated to the protein keyhole limpet hemocyanin (KLH), has been in c linical evaluation. Although this and other carbohydrate vaccines have been shown to induce antibody responses, there are currently no quantitative da ta on the antibody levels achieved in immunized patients by these or other anti-cancer vaccines. We report herein an efficient route to complex synthe tic oligosaccharides attached to an affinity matrix for identifying and iso lating antibodies elicited against such a carbohydrate-based vaccine in hum ans. Pre- and postvaccination profiles from serum samples of patients immun ized with globe H-KLH were compared. All anti-globe H antibody activity was efficiently separated from other serum constituents. The isolated antibodi es were readily quantified, and their specificities were analyzed. Since no comparable data were available on antibodies resulting from the vaccinatio n of other cancer patients, we compared the observed levels with those quot ed in studies with bacterial polysaccharide vaccines that had been quantifi ed, Remarkably, cancer patients immunized with globe H-KLH produce anti-glo be H antibody levels often exceeding those formed by immunization with bact erial polysaccharides. In addition, substantial quantities of both Igt and IgM antibodies were elicited, clearly indicating a class switch to IgG, Tak en together, these analyses serve to clarify several aspects of the immune response to the vaccine and give several new insights to the carbohydrate-b ased vaccination strategy. Furthermore, antibodies so isolated could well h ave applications in clinical therapy.