Immunity and Antibody Formation Induced by Intraperitoneal or Subcutaneous Injection of Krebs-2 Ascites Tumor Cells Treated With Influenza Virus

Summary

Incubation of Krebs-2 ascites tumor cells with influenza virus at high multiplicity reduced the tumor-producing capacity of cell suspensions. These virus-treated cells could then be used as an antigen to stimulate resistance to the tumor when given intraperitoneally. An attempt was made to define the optimal conditions of virus treatment for a nonlethal but effective antigen. Since less than 10 Krebs-2 cells given intraperitoneally produced lethal ascites tumors in most Swiss mice, immunization with fully viable cells by this route was virtually impossible. But some mice could be given large numbers of cells subcutaneously, with production of immunity to intraperitoneal challenge. Virus-treated cells given subcutaneously failed to immunize. Quantitation of the cell dose required for immunization indicated that a single intraperitoneal injection of 10³ to 10⁴ virus-treated cells produced some resistance, but multiple doses of 10³ to 10⁵ cells were more effective. Similar data were obtained by subcutaneous immunization with untreated cells against intraperitoneal challenge. The serum from mice hyperimmunized with Krebs-2 cells gave specific reactions by fluor-escein-antibody labeling of surface antigens. With other tumors a reaction was observed with 1 to 5 percent of cells in a suspension. When complement was present, the labeling of surface antigens of Krebs-2 cells was followed by cytolysis.