A Persistent Hypersusceptibility Induced in Rabbits with an Homologous Tumor Material

Abstract

A single injection of a filterable material from homologous tumor tissue prepared by prolonged anaerobic refrigeration will render the rabbit host more susceptible to the inoculation and increase the malignancy of the Brown-Pearce rabbit tumor. The dosage employed may vary from 0.2 to 0.5 cc. of a 1–5 dilution of the material. 1 The material is equally active when inoculated either 2 weeks before or 2 weeks after the tumor inoculation. In a previous experiment injection of the material 3 times at 2 month intervals led to increased susceptibility instead of to an immunity to this tumor.

This paper reports a second series in which 5 male rabbits were injected 8–10 times at intervals varying from 2 weeks to 2 months. The rabbits were then permitted to rest for 7 months, during which period no treatment was given. At the end of this period the 5 rabbits (experimental group) and 14 control rabbits (adults of the same sex, size, origin, and breed but almost a year younger) were inoculated intratesticularly with fresh Brown-Pearce tumor. The experiment was terminated at 2 months. The incidence of primary testicular tumors was 4 (80%) for the experimental group as compared with 11 (78.6%) for the control group; the cubic volume of the 4 primary tumors at autopsy in the experimental group was 15.5 cc. as compared with 10.0 cc. for the 11 primary tumors in the control group; the incidence of metastatic tumor in the experimental group was 4 (80%) as compared with 9 (64.3%) for the controls; the cubic volume of the metastatic tumor per animal with metastases was 175 cc. in the experimental as compared with 38.3 cc. for the control group; the average number of metastatic foci was 22.0 for the experimental as compared with 9.0 for the control group; the total mortality for all animals inoculated was 73.4% in the experimental as compared with 46.4% for the control group; the total mortality for all animals with tumor was 91.8% in the experimental as compared with 59.1% for the control group; the average longevity for all 5 animals in the experimental group was 50.8 days as compared with 58.6 days for the 14 animals in the control group.