Opsonization of antitumor reactive lymphocyte in SJL/J mice bearing spontaneous or transplanted reticulum cell sarcomas (RCS).

Radiolabelled antitumor reactive T lymphocytes (ARC) were prepared in vivo by immunization of SJL/J mice with mitomycin C inactivated syngeneic LA-6 tumor cells followed by injection of 125IUdR to label dividing cells. These ARC were specifically diverted to the liver when injected in LA-6 tumor-bearer serum and injected i.v. into normal SJL/J mice. Likewise, SJL/J anti-Balb/c ARC were diverted to the liver of SJL/J mice bearing spontaneous reticulum cell sarcomas (RCS) carrying Balb/c cross-reactive antigens but not in mice with Balb/c negative neoplasms. Mice with Balb/c positive tumors also had circulating ARC opsonizing factors. These results suggest a mechanism for the survival of antigenic tumors involving macrophages and ARC opsonizing (ARCO) factors. A novel approach to immunotherapy is discussed.