Selective XYZ Factor in C57 Black Mammary Carcinoma Eo771

Abstract

12 expts. were made with mouse mammary carcinoma Eo771 (C57 black origin) using 250 C57 black mice. Complementary use was made of mouse mammary carcinomata 241-5, 241-16 (C57 black origin), 15091a (strain A origin), and Barrett (C3H origin). A highly selective XYZ factor (entirely comparable with those described for the Brown-Pearce rabbit tumor and Bashford mouse mammary carcinoma 63), resulting in enhanced tumor growth, was found to be uniformly present in the frozen Eo771 tumor tissue.. The XYZ effect was present when the XYZ factor was derived from the homologous tumor and absent when derived from a heterologous tumor, even from other mammary carcinomata of the same highly inbred C57 black strain. This high tissue selectivity of the XYZ factor was not limited or detd. by the host into which the tumor cells were transplanted. The factor was equally effective in homologous or heterologous transplanted hosts, so long as the tumor cells were viable in the foreign host. XYZ factors have thus far been proven for only 4 transplanted neoplasms of mice and rabbits all of which are Grade III-IV by histologic grading. No such factors have been observed in adult tissues, leukemias, benign and low-grade tumors.