[The effect of Listeria factor Ei, BCG vaccine and a combination of both on the growth of experimental syngeneic tumors in inbred mice].

The investigation assessed, whether a nonspecific single and repeated immunization induced by Listeria monocytogenes Ei factor, BCG vaccine and their combination influences the growth of transplanted syngenic methylcholanthrene tumour depending on tumor graft cellularity. The cellularity of 10(4) and 10(5) were investigated. Tumour growth was examined 10 and 17 days after the inoculation. It has been found that single Ei factor administration did not influence the tumour growth. Single BCG vaccine favourably influenced the tumour growth, but in progressing time and cellularity the effect was failing. In combination of BCG vaccine and Listeria Ei factor the antitumour effect appeared to be most profound. In progressing time after the tumour grafting and graft cellularity the effect was disappearing. It was probably due to the fact that immunotherapy fails to control tumour mass with high cellularity. The antitumour effect potentiation by combination of BCG vaccine with Ei factor suggests a way to a possible combined antitumour immunotherapy.