Effects of antibodies to choriogonadotropin in malignant growth: I. Rat 3230 AC mammary adenocarcinoma

To determine whether the in vivo production of antibodies against choriogonadotropin (CG) could modify the relationship between host and malignant growth, the effects of preimmunization with a conjugate of the β‐subunit of CG and tetanus toxoid (CGβ‐tt) on the development and growth of lung metastasis following I.V. injection of R 3230 rat mammary adenocarcinoma cells into Fischer 344 female rats have been investigated. This neoplasm has been previously demonstrated to synthesize CG‐like material. A test group of 70 animals and two matched control groups of 15 animals each were used. One of the control groups was untreated and the other received tetanus toxoid only. All the control animals had multiple lung foci of neoplastic cells ten days after seeding, as has been previously observed, and CG antibodies were undetectable. In contrast, a significant titer of anti‐CG was found in all preimmunized animals. At the same time, the pretreated animals rarely had a few small neoplastic nodes in the entire lung sections at the standard 8–10 days post‐seeding. The protective effects of preimmunization with CGβ‐tt were further demonstrated by the animals living 20 days post‐seeding, the absence of lung pathology in the ones killed thereafter, and by six animals that were left alive and have not shown any deterioration for more than six months after the administration of the cell suspension.