Genetic control of Propionibacterium acnes-induced protection of mice against Babesia microti.

Using various strains of inbred mice, we found that Propionibacterium acnes-induced protection against the hemoprotozoan parasite Babesia microti was controlled by a dominant gene(s) not linked to the major histocompatibility gene (H2) complex of mice. P. acnes-induced resistance to infection was not merely an amplification of the normal immune response to B. microti, since innate resistance to infection was controlled by different genes. Expression of the nonspecific protection induced by P. acnes was found to be transferable with cells of bone marrow origin, and it did not necessarily accompany the induction of hepatosplenomegaly. The implication of these results for the understanding of the mechanism of P. acnes-induced protection is discussed.