IMMUNOLOGY OF SPONTANEOUSLY ARISING RAT MAMMARY ADENOCARCINOMAS

The immunogenicities of nine spontaneously arising mammary adenocarcinomas were assessed following pre‐treatment of syngeneic female rats with heavily irradiated tumour or excision of subcutaneously developing tumour grafts. One tumour (SP4) was moderately immunogenic and a weaker level of resistance could be evoked against two others. With these three examples, induced resistance was specific to the immunizing tumour and no instances of antigenic cross‐reaction were detected. No resistance could be induced against the remaining tumours, even though challenge inocula of as few as 102 or 103 cells were tested in pre‐irradiated hosts. There was no correlation in this series between tumour immunogenicity and latent period of development. Peritoneal exudate cells from rats immune to tumour Sp4 were shown to suppress the growth of this tumour in normal pre‐irradiated recipients, but relatively large numbers of immune cells were necessary and their effectiveness was not consistent, factors which reflect the low immunogenicity of the tumour. These peritoneal cells had no influence on the growth of any other of the spontaneous rat mammary adenocarcinomas, further confirming the individuality of the TSTAs on tumour SP4. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company