Pulmonary clearance of Mycoplasma pulmonis in C57BL/6N and C3H/HeN mice.
In C57BL/6N and C3H/HeN mice known to be free of all murine pathogens and matched for age, sex, and environmental factors, pulmonary clearance was measured over a 72-h time period after exposure to infectious aerosols of 35S-labeled Mycoplasma pulmonis. Reduced clearance of M. pulmonis in C3H/HeN mice relative to C57BL/6N mice was primarily due to impaired mycoplasmacidal activity in the lungs of the C3H/HeN mice. The C3H/HeN mice also had a slightly slower rate of mechanical transport of radiolabel from the lungs in the first 4 h after infection relative to the C57BL/6N mice but not at any later times. By 72 h after infection (relative to 0 h, C3H/HeN mice had an over 4,000% (1.75 X 10(7) versus 4.30 X 10(5] increase in neutrophils and an over 18,000% (more than 2 orders of magnitude) increase in numbers of M. pulmonis recovered from mechanically disaggregated lungs. In contrast, C57BL/6N mice reduced the number of M. pulmonis present by over 83% (nearly 2 orders of magnitude) before any increase in inflammatory cells, which was only a slight increase in lymphocytes and macrophages at 24 h after infection. These results directly link decreased mycoplasmal pulmonary clearance in C3H/HeN mice with the increased susceptibility to, and severity of, murine respiratory mycoplasmosis observed in this strain. The resistance of C57BL/6N mice appears to be related to nonspecific host defense mechanisms responsible for limiting the extent of infection.
Parker
R F
RF
Department of Comparative Medicine, School of Medicine, University of Alabama, Birmingham 35294.
Davis
J K
JK
Blalock
D K
DK
Thorp
R B
RB
Simecka
J W
JW
Cassell
G H
GH
D000336:Aerosols; D000818:Animals; D007249:Inflammation / Q000473:pathology; D007958:Leukocyte Count; D008168:Lung / Q000382:microbiology* / Q000473:pathology; D051379:Mice; D008815:Mice, Inbred Strains; D009079:Mucociliary Clearance; D009174:Mycoplasma / Q000276:immunology*; D009175:Mycoplasma Infections / Q000276:immunology* / Q000473:pathology
D000336:Aerosols