Increased susceptibility to primary infection with Listeria monocytogenes in germfree mice may be due to lack of accumulation of L-selectin+ CD44+ T cells in sites of inflammation.
The host defense of germfree (GF) mice against primary infection with Listeria monocytogenes was compared with that of specific-pathogen-free (SPF) mice. In SPF mice, the numbers of bacteria in the peritoneal cavity, liver, and spleen decreased gradually to undetectable levels by day 8 after intraperitoneal infection with a sublethal dose (2 X 10(3) CFU) of L. monocytogenes. On the other hand, the elimination of bacteria in these organs of GF mice was significantly impaired at this stage after inoculation. We have reported previously that T cells coexpressing L-selectin and CD44 play an important role in protection against L. monocytogenes through trafficking to sites of inflammation. Consistent with our previous findings, the number of unique L-selectin+ CD44+ T cells in the peritoneal cavity was remarkably increased on day 8 after infection in SPF mice, whereas such an increase was not evident in GF mice at this stage. Listeria-specific T-cell proliferation was normally detected in the lymph node cells of GF mice inoculated with L. monocytogenes, whereas the T-cell-proliferative response of the peritoneal exudate cells of GF mice was significantly impaired compared with that of SPF mice. These results suggest that the priming of T cells against listerial antigens normally occurs in the peripheral lymphoid organs of GF mice but the trafficking of the activated T cells to the inflamed sites may be severely impaired in GF mice, resulting in increased susceptibility to infection with L. monocytogenes.
Inagaki
H
H
Laboratory of Host Defense and Germfree Life, Research Institute for Disease Mechanism and Control, Nagoya University School of Medicine, Japan.
Suzuki
T
T
Nomoto
K
K
Yoshikai
Y
Y
D000818:Animals; D001201:Ascites / Q000473:pathology; D004198:Disease Susceptibility; D005260:Female; D005434:Flow Cytometry; D005856:Germ-Free Life / Q000276:immunology*; D018960:Hyaluronan Receptors / Q000032:analysis*; D007249:Inflammation / Q000276:immunology / Q000473:pathology; D019041:L-Selectin / Q000032:analysis*; D008089:Listeria monocytogenes / Q000472:pathogenicity; D008088:Listeriosis / Q000276:immunology*; D008099:Liver / Q000473:pathology; D008198:Lymph Nodes / Q000473:pathology; D008213:Lymphocyte Activation; D051379:Mice; D008813:Mice, Inbred ICR; D010529:Peritoneal Cavity / Q000382:microbiology; D013047:Specific Pathogen-Free Organisms / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology*
D018960:Hyaluronan Receptors; D019041:L-Selectin