Comparative study on the immunostimulatory potency of different Propionibacterium strains.

198 strains of Propionibacterium acnes, P. avidum, and P. granulosum were tested for their immunostimulatory potency using splenomegaly as index of stimulation, the activity differed widely from strain to strain. The antitumor and antimetastatic properties of six strains with differing stimulation activities were carefully examined. A close correlation between spleen enlargement and antitumor effects could be observed. The simple spleen enlargement test is recommended for determination of the immunopotency of propionibacteria and for the standardisation of vaccine preparations.