Interference by cortisone with endotoxin's adjuvator action on transplantation of a mouse tumour.

Observations on the in vivo plating of mouse mammary tumour are extended by making counts of tumours at a significantly earlier phase of development than in previously reported work. In the experiments now described, most of the growth of the tumours has been without benefit of stroma. The noteworthy economy of the experimental method is discussed. The persistence of endotoxin's adjuvator effect on such tumour counts is tested in the face of gamma irradiation and cortisone. Cortisone, it is found, offsets endotoxin's adjuvator action; irradiation does not. Antagonism between endotoxin and cortisone, in this system with tumour cells plated in vivo, seems to indicate that endotoxin's enhancing effect depends more on inflammatory than on immunological factors.