Effect of trypan blue upon distribution of metastases and transplants of rabbit VX2 and Walker rat 256 tumors.

One approach to the study of cancer is the investigation of natural or acquired host defense mechanisms. In 1932 Foulds (6) compared the distribution of intravenous (I.V.) transplants of Brown-Pearce carcinoma in trypan blue-injected rabbits with that in controls. He found an increased incidence of splenic, hepatic, and pulmonary growths in trypan blue-treated animals and suggested that phagocytized trypan blue depressed the host animals' reticulo-endothelial system (RES). Data which also have been suggested by others to support the concept that the RES functions as a defense mechanism against certain aspects of malignancy include the findings that trypan blue abrogates the natural and induced immunity of certain animals to tumor takes (11, 12), that subcutaneous (S.C.) injections of carotin in rats was followed by disappearance of the Flexner-Jobling carcinoma and the Jensen sarcoma (13). Perhaps this concept is also supported by the findings that there is a unique paucity of lesions in the spleen following inoculation of VX2 or Walker rat ~ 6 tumors (1, 2, 9, 14, 17). As a basis for further investigation into any possible role of the RES in relation to the distribution and growth of metastases, these experiments were conducted to establish the effect of trypan blue upon distribution of VX2 rabbit carcinoma and Walker rat carcinosarcoma 256, and to compare the results with those previously observed by Foulds with the Brown-Pearce tumor (6).