Further Studies on Oncolysis and Tumor Immunity in Rats

Abstract

Alcoholic extracts of rat sarcoma concentrated in vacuum to an alcohol content of 30 per cent resulted in a yellow fluid that had a hydrogen-ion concentration of 6.4 to 6.8. A precipitate occurred on addition of water, acid or sodium chloride but not on the addition of a phosphate buffer at pH 7.6 and μ = 0.1. The color reactions in nucleic acid diphenylamine, orcinol, carbazole, and tryptophane perchloric acid indicate a closer relationship to the ribose type than to the desoxyribose type nucleic acid. Chemical analyses showed presence of nitrogen and some phosphorus. More nitrogen was present than could be accounted for as nucleic acid. Some of it was probably protein nitrogen, as shown by the biuret test and also by the presence of extra selective absorption at a wave length of 2800 Å. Spectral absorption analyses of the rat sarcoma extracts exhibited a maximum absorption in the ultraviolet at a wave length of 2550 and 2600 Å, whereas similar extracts of human carcinoma showed one at 2500 Å. The former had a minimum absorption at wave length 2400 Å and the latter at 2300 Å. Intratumoral injection of rat sarcoma extract brought about oncolysis in 203 out of 210 rat tumors treated. Injection of human carcinoma extract into rat sarcoma showed some oncolytic action; tumors were destroyed in 15 of 25 treated rats. One hundred and forty nine of the 203 rats in which tumors had been destroyed by the injection of rat sarcoma extract were tested for resistance to tumor growth and proved to be resistant to further growth of rat sarcoma.