Legionella pneumophila growth in macrophages from susceptible mice is genetically controlled

Growth of the intracellular opportunistic bacterium Legionella pneumophila in macrophages from A/J mice is a vigorous as growth in macrophages from susceptible guinea pigs and human monocytes, whereas growth is inhibited in macrophages from other mouse strains, such as nonpermissive BALB/c mice. Permissiveness versus nonpermissiveness of macrophages from A/J versus BALB/c mice appeared to be controlled by a genetic mechanism dependent upon a single gene or a closely clustered family of genes. Susceptibility versus resistance of macrophages from F1 offspring of these two strains of mice and macrophages from backcrossed mice prepared from F1 hybrids and the original parental strain showed a segregation of permissiveness for growth of Legionella in vitro, consistent with genetic control.