Genetic control of macrophage susceptibility to infection by Legionella pneumophila.

Legionella pneumophila readily grows in cultures of thioglycollate (TGC)-induced macrophages (MPs) from A/J mice, but not in MPs from BALB/c mice or other mouse strains. In the present study, the growth of Legionella pneumophilia in MPs from A/J and BALB/c mice, as well as hybrids of the two strains and back-crossed mice, was investigated to determine whether the permissiveness of growth of these bacteria was due to an inherited trait of the MPs. The MPs from all A/J mice supported the growth of Legionella, regardless of whether they were obtained from TGC or casein injected donors, but the cells from the mice given TGC supported growth of L. pneumophila much better than cells from mice injected with casein. Furthermore, MPs obtained from all BALB/c mice treated with either TGC or casein were nonpermissive for the growth of L. pneumophila. MPs from approximately 46% of the back-crossed ACF1 to A/J mice were permissive for L. pneumophila growth, while MPs from all ACF1 to back-crossed BALB/c mice were found to be nonpermissive. MPs from approximately 19% of ACF2 mice were permissive for L. pneumophila. Killing activities of MPs using temperature sensitive mutants of Salmonella typhimurium were variable and did not correlate with permissiveness or nonpermissiveness for growth of L. pneumophila.(ABSTRACT TRUNCATED AT 250 WORDS)