Abstract
Cross-reactivities between chemically induced rat tumors and fetal tissues were examined by the migration inhibition test. Wistar/Fib adult rats were immunized by intracutaneous injection of Freund incomplete adjuvant with or without the extracts of various fetal tissues (one-week whole fetal tissue, two-week fetus without brain and spinal cord, and two-week fetal brain). A mixture of thymic and lymph-node cells was used as migration cells. Peripheral neurinomas (T1 and T3) and oligodendroglioma (T2) were induced by ethylnitrosourea with single intraperitoneal injection in pregnant rats in the third week of gestation; 3M KCl extracts of these tumors served as antigens. The animals sensitized by two-week fetus reacted with all neurogenic tumors although in half of them (4/8) no significant differences from the reaction of the lymphoid cells sensitized by Freund incomplete adjuvant alone were demonstrated. The lymphoid cells sensitized by one-week fetus showed the weakest responses (especially in the reaction with T3 tumor) among all fetal extracts.
The T1 tumor was also suggested to have brain specific antigens. When the lymphnode cells served independently as the migration cells, it was very difficult to obtain positive results which were easily obtained by a mixture of lymph-node cells and thymic cells. However, the lymph-node cells sensitized by one-week fetus reacted much more strongly than the mixture of thymic and lymph-node cells.
In vivo tumor rejection studies on the embryonic tissue of immunized rats are now in progress.
