Antibody mediated suppression of tumor growth. III. Molecular assay of murine IgG1 alloantibody required to cause tumor suppression in vivo

A radioimmunoassay was used to quantitate the number of tumor cell bound IgG1 anti tumor antibody molecules required to cause suppression of tumor growth in C3H mice. Radiolabeled anti IgG1 was used to detect cell bound IgG1 antibody. The assay was calibrated using TNP coupled tumor cells that had a known number of bound IgG1 anti DNP molecules. Between 70,000 and 130,000 IgG1 anti tumor antibody molecules per tumor cell were sufficient to cause 50% suppression of tumor growth in mice inoculated with approximately 50,000 tumor cells.