Intradermal Transplantation in Mice of Small Numbers of Sarcoma Cells Followed by Tumor Growth and Regressio &

Relatively small numbers of Sarcoma I cells were trans planted intradermally in A/WySn mice to study the course of growth when the size of the transplant is comparable to an early stage of spontaneous cancer. Transplants of 31 to 32,000 cells took one of three courses: no apparent growth; development of tumor followed by regression; on prognes sive growth. Transplants of 8,000 cells were the most evenly divided among these three courses and were selected for further study. Bilateral tumors took the same course to regression or to continued growth with significant fre quency. There was complete correlation between regnes sian of a tumor and immunity to a challenge made 1 to 5 weeks after the original transplant. Persistent tumors had a similar relationship, but the immunity was less complete. Limited, inapparent growth, followed by regression, was indicated in some mice, simulating immunological surveil lance. Serum from such mice, when administered systemi cally in other mice, apparently induced enhancement of intrademmal transplants.