Abstract
Sarcoma 180 cells were implanted in C3H/He mice and blastogenic responses (PHA, Con A, LPS) of spleen cells were observed time serially to determine the relationship with concomitant immunity. Blastogenic responses dropped markedly in the early phase after implantat due to immunosuppression from the tumor, but they later recovered to a certain level. Product of the cpm value for PHA response and the spleen cell population (the number of cells responsive to PHA) showed a close correlation with concomitant immunity (resistance towards tumor) . Concomitant immulity was established when the value became 1.5-fold the normal. The correlation of the two became even more definite by the implantation study following whole body irradiation. When the regression of tumo mass was brougt about by irradiation, cells responding to PHA maintained a high lewel for a long time. The resietance towards tumor was also maintained prolongedly. Contrarily, when the tumor was resected, the PHA responding cells decreased rapidly and the resistance towards tumor also vanished quickly. For the maintenance of resistance against tumor, the inactivated tumor cells should be retained in the body for long and irradiation was favorable to this end. Relationship between blastogenic responses and spleen cell population is also associated with this phenomenon.
