Effect of the H37Ra Strain of M. tuberculosis and of a Mycobacterial RNA Fraction on Tumor Growth 1

Abstract

Summary

Data are presented to show that both an H37Ra strain of Mycobacterium tuberculosis and a ribosomal RNA fraction from this strain are effective inhibitors of tumor growth in mice. Mice were pretreated with tubercle bacilli or RNA fraction and challenged 5 weeks later with mixtures of tumor cells and the respective pretreatment agents. Comparative data with BCG are presented. Inhibition did not appear to be due to any direct toxic effect of tubercle bacilli or ribosomal RNA fraction on tumor cells. The necessity, for an inhibitory effect, of tuberculin hypersensitivity was deemed unlikely because the ribosomal RNA fraction neither induces nor provokes tuberculin hypersensitivity. The inhibition realized with mycobacterial extract avoids the risk to the tumor-bearer of viable organisms.