Induction of immunity to a human osteosarcoma-associated antigen in mice using anti-idiotypic antibodies.

Polyclonal rabbit anti-idiotypic antibodies (Ab2) were produced and analyzed for their ability to stimulate humoral immunity against a human tumor-associated antigen (TAA) in BALB/c mice. Murine monoclonal antibody (Mab) OSA-1 recognizes an 85,000-Da TAA present on both human osteosarcoma tissue and osteosarcoma cell lines. Rabbits were immunized with OSA-1 (Ab1) to produce Ab2. The polyclonal Ab2 were shown to react against an idiotope located at or near the antigen combining site of Ab1. Ab2 were demonstrated to be potent inhibitors of TAA binding to Ab1. BALB/c mice were immunized with this Ab2 preparation and then tested for the presence of osteosarcoma TAA reactive antibodies. Sera from Ab2-immunized mice were shown by Western blot to contain antibodies whose specificity resembled Ab1. Thus, immunization with polyclonal rabbit Ab2 was shown to stimulate production of Ab3 in mice which reacted against a human osteosarcoma TAA.