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 by 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 appriximately 50,000 tumor cells.