[Effect of the age of the mouse on the action of Corynebacterium parvum in inhibiting the growth of 2 syngenetic tumors].

The antitumor properties of Corynebacterium parvum have been studied in Mice of different ages of two inbred strains: XVII Mice and C3H Mice grafted with syngeneic tumors. The antitumor protection was very weak in young Mice: no effect on mortality rate, only an increase in mean survival time was observed. The highest level of protection was obtained in 2-5 month old Mice (100% of survival) In aged Mice this antitumor protection decreases more rapidly in C3H Mice than in XVII Mice. It is interesting to note that 21 day old XVII Mice and 25 day old C3H Mice, non weaned, are partially protected by C. parvum (50% survival), while treated Mice of the same age, already weaned, are not.