Implications of the Fetal Antigen Theory for Fetal Transplantation¹ Free

These experiments were carried out to test the hypothesis that fetal cells contain distinctive transplantation antigens capable of arousing cell-mediated immunity and, if such antigens exist, to determine whether they could influence the growth of syngeneic tumors. If fetal antigens do arouse cell-mediated immunity, the growth of fetal tissues in a normal syngeneic mouse should be inferior to that in immunosuppressed mice.

When syngeneic 11-day fetal tissue fragments were implanted into normal adult male mice, growth was poor and showed a restricted variety of tissues with a moderate lymphocyte infiltrate. In similar adult mice made immunologically deprived by thymectomy and lethal irradiation followed by bone marrow reconstitution, these fetal implants grew larger and with a profusion of tissue types. There was no lymphocytic infiltrate. Adult syngeneic tissue homogenates grew well in both environments.

When normal adult mice were pretreated with syngeneic 12-day fetuses, the test fetal implant grew larger and with greater histological variety than in mice not so pretreated.

The effect of fetal tissues inocula on the induction and transplantation of tumors was also studied. Pretreatment of adult mice with fetal tissues prolonged induction times of tumors produced by 20-methylcholanthrene, but inoculation of fetal tissues during the induction period accelerated the appearance of tumors. Pretreatment with irradiated fetal tissues conferred protection against transplantable Meth A tumor cells.

These results suggest that syngeneic fetal tissues provoke a transplantation reaction in normal adult mice. Furthermore, the results confirm a relationship between fetal and tumor antigens so that treatment with fetal tissues may influence tumor growth.