Abstract
That growth promoting substances are present in transplanted tumors has been known for a long time. But that they can exercise a profound influence over the metastatic phase of malignancy, that their effects in sensitizing the host to a malignant growth can be more or less permanent, or that they have species and tissue limitations in their activity is only now being demonstrated. 1 Thus, a filterable material from the Brown-Pearce rabbit tumor has been found to enhance every observed phase of the growth of this tumor, both local and metastatic. A species limitation has been noted in that the material from the rabbit tumor would not enhance the growth of mouse carcinoma 63 or mouse sarcoma 180. Rabbits treated with the material were still profoundly hypersusceptible to both local and metastatic phases of the Brown-Pearce tumor 7 months after the last injection. 2 The growth promoting material described by Haaland 3 and Leitch 4 in mouse carcinoma 63 has been found to enhance growths of the same tumor but has had no enhancing effect on the growth of the rabbit tumor or the growth of mouse sarcoma 180.
That enhancing materials are to be found in sarcomata seemed evident from the work of Flexner and Jobling 5 and of Chambers and Scott. 6 To test the specificity and biology of sarcoma enhancing materials, experiments were undertaken of which the first 3 are here reported. In each experiment tumor tissue from mouse sarcoma 180 was anaerobically refrigerated for 14–60 days at 24°F., minced and ground without sand, and emulsified with normal saline (dilution 1–10). In one experiment the emulsion was filtered through a Berkefeld “V” candle. Of this emulsion 0.1 cc. was injected into the left groin of 10 mice; 2 weeks later the 10 mice and 10 control mice not previously treated were inoculated in the same groin with fresh sarcoma 180.
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