Suppression of tumor growth by in vivo administration of a recombinant human-mouse chimeric monoclonal antibody.

The in vivo administration of a recently described recombinant human-mouse chimeric antibody specific for a human common acute lymphocytic leukemia antigen (cALLA) caused significant inhibition of the tumorigenic growth of human leukemic cells (Manca cells, expressing cALLA on the surface) which were implanted into nude mice. Intratumor as well as intraperitoneal administration of the human-mouse chimeric antibody repressed the tumor growth of Manca cells in nude mice. In order to investigate the in vivo localization of the antibody molecules, the chimeric antibody was labeled with radioiodine (131I) and injected into nude mice transplanted with Manca cells. The labeled antibody was significantly localized in the tumor and the location of the tumor was successfully visualized by scintiphotoscanning. These results indicated that the recombinant human-mouse chimeric antibody can exert a significant antitumor effect in vivo and can be utilized for radio-immunoimaging. Since the chimeric human-mouse monoclonal antibody would be expected to have a much lower antigenicity to humans and much higher efficiency in the interaction with human effector cells, such recombinant chimeric antibodies may be beneficial for immunotherapy and immunoimaging of cancer patients.