1967 Volume 22 Issue 1 Pages 31-36
After finding a remarkable decrease in the complement in the sera of patients with fulminant form of dysentery in 1952, natural sensitization by E. coli, representative of normal intestinal flora, has been studied by Matsumura, one of the authors, et al. with the following results; bacterial cross allergic reaction between E. coli and Sh. flexneri, having common antigen, natural sensitization by E. coli, and prenatal congenital sensitization by E. coli, etc. Pyrogenic activity of the endotoxin derived from gram-negative bacteria was also assumed to be induced by antigen-antibody reaction on the basis of natural sensitization by normal intestinal flora, from the study of parallelism between the acquisition of febrile tolerance and the increase of the anti-endotoxin titer in sera, in the rabbits.
The main project was undertaken to ascertain whether natural sensitization by resident E. coli plays some roles in the mechanism of regression of tumor by the endotoxin extracted from resident E. coli.
Rats of the Wistar colony, bred at the Gunma University, harbored GP5 (authors' type) in their intestine as endemic strain. GP5 was identified as E. coli O89::H6. Of 2, 302 cultures of enteric bacteria isolated for about 4 years, 921 were identified as GP5. Of 23 rats which could be studied for 6 months, 9 always yielded GP5 and 8 never did in 26 cultures of feces. A well host-parasite relationship was indicated. Experimental animals were divided into 2 groups. Of 8 cultures for about 2 months, “GP5-positive rats” yielded GP5 in 6 to 8 cultures, while “GP5-negative ones” never did. The endotoxin extracted from GP5 with phenol/water was injected intravenously and Yoshida sarcoma was used, being inoculated subcutaneously. The results were as follows. In the case of 1 to 4 weekly intravenous injections of 0.1 mcg dose, 11 of 13 “GP5-positive rats” and 13 of 14 “GP5-negative ones” showed complete regression. In the case of 2 to 5 intravenous injections of 0.01 mcg dose, 16 of 21 “GP5-positive rats” and 6 of 20 “GP5-negative ones” showed complete regression. In the case of 2 to 4 intravenous injections of 0.001 mcg dose, 3 of 10 “GP5-positive rats” showed complete regression.
As to the regression rate in the case of 0.01 mcg injection dose, it was higher in the “GP5-positive rats” than in “GP5-negative ones”, while both groups showed almost the equal rate in the case of 0.1 mcg injection dose. These results suggest that regression of tumor treated with bacterial products would occur on the basis of natural sensitization, derived from not only postnatal sensitization but also prenatal congenital one.
