Report III. The Humoral Defensive Power of Rats Against Mycobacteria (Study on the Susceptibility of Rats to Various Strains of Mycobacteria)

Abstract

In order to explain the mechanism of the high native resistance of albino rats to tuberculosis, growth-experiments in vivo using various strains of mycobacteria were carried out using the chamber method. Virulent tubercle bacilli (human and bovine) could not grow at all in the O-and K-chambers. These results are different from results obtained by experiments in rabbits, in which bacilli were capable of growth in the O-chamber, but not in the K-chamber. It may be also concluded that the high molecular factor of body fluid in rats is tuberculostatic, although the high molecular factor of rabbit's body fluid acts to stimulate-growth. The low molecular factor of rats is of course growth-inhibiting, as it is in rabbits. Therefore, it may be that this property of body fluid in rats plays a very important role in the high resistance to tuberculosis of this animal. In vitro experiment including anaerobic cultivation and slide culture methods were performed to support the in vivo findings described above, but it has been shown that these in vitro culture methods are inadequate for the resolution of the problem of the host-parasite relationship. Experiments using the chamber technique showed that cortisone administration to rats has no marked influence on the effect of body fluid on the growth of virulent tubercle bacilli in vivo, especially in the enhancement of multiplication. This discrepancy of results between rats and rabbits might be questioned in the future.