A Species Limitation of an Enhancing Material Derived from a Mammalian Tumor

Abstract

In an effort to differentiate the material derived from the Brown-Pearce rabbit tumor from other enhancing materials it seemed desirable to know whether it would enhance various diseases and tumors, both in the same and in different species. To this end a series of experiments was made with a Bashford mouse carcinoma (No. 63). The experiments were distributed at approximately 6 weeks intervals between January, 1932, and January, 1933, each experiment consisting of 30 mice divided into 3 groups of 10. Enhancing material prepared from Brown-Pearce tumor tissue and enhancing material prepared in an entirely similar manner from the Bashford tumor itself were injected subcutaneously into the left groins of the animals of Groups 1 and 2 respectively. No tumor growths resulted. Twelve to 18 days later the animals of these 2 groups together with those of the third, not previously injected, were inoculated with grafts (Exps. 1-6) or with a saline emulsion (Exps. 7-10) of fresh Bashford tumor tissue (Table I). Observations were made on the incidence and the size of the primary tumors resulting. Of the 97 mice treated with the rabbit tumor material 46 (47.4%) had primary tumors at 21 days as compared with 57 (57.5%) among the 99 control mice and 67 (67%) among the 100 mice treated with material from the Bashford tumor itself. Such an excessive variability would not be expected to occur by accident more often than twice in 100 similar experiments with 300 mice (x2—7.7, n—2, P—0.02). Treatment of the mice with the rabbit tumor material seemed to result in fewer takes, while treatment of the mice with the mouse tumor material seemed to result in an increased number of primary tumors, the difference between the 2 series being significant when compared directly (x2—7.7y n—1, P—0.01—).