PROCESS OF ESTABLISHMENT OF REJECTION

Abstract

Yoshida sarcoma was, first, transplanted on the right side of the back of Donryu rats. Thereafter the second tumor was transplanted on the left side of the back after interval of 1 to 21 days. Unsuccessful inoculation of the second tumor was regarded as tumor rejection. In this system, rejection was made up three days after the transplantation of the first tumor. In order to evaluate the rejection numerically, whole irradiation with ⁶⁰Co-γ-ray was added to suppress some extent of the rejecting power. Results are as follows.
1) Establishment of rejection was 3 days after first tumor transplantation.
2) When rats were irradiated before the establishment of tumor rejection, the extent of establishment was decreased. The earlier irradiation was performed, the more this establishment prolonged.
3) Rejection was suppressed, when 50 cads was irradiated immediately after the establishment of rejection. Irradiation of 50 rads on 3 days after the establishment of rejection failed to suppress rejection, while irradiation of 100 rads suppressed rejection.
4) The smaller the dose was, the earlier the rejection recovered.
5) The extent of rejection was increased by 2 times of inoculated second tumor cell.
6) This extent of rejection was gradually increased from the time of inoculation of first tumor.