Examination of host defense factors responsible for experimental chronic respiratory tract infection caused by Klebsiella pneumoniae in mice.
We have studied the host defense factors that operate during the course of chronic respiratory tract infection caused by Klebsiella pneumoniae 27 in CBA/J mice. A large number of polymorphonuclear leukocytes (PMNs) rapidly infiltrated the alveolar spaces after infection. Treatment with cyclophosphamide (CY) before infection greatly reduced the infiltration of PMNs and caused an increase in bacterial counts. CY treatment of mice in the chronic phase also caused bacterial proliferation in the lungs. The administration of a high titer immune serum efficiently reduced the bacterial counts in the lungs during the early phase but not during the chronic phase. The proliferation of bacteria induced by CY treatment was not suppressed by the administration of the immune serum in either phase. When the mice were exposed to an aerosol containing Pseudomonas aeruginosa P9 in the chronic phase, the organisms from the secondary infection were eliminated from the lungs in the same manner as in the case of primary infection with P. aeruginosa. Thus, PMNs seem to play an important role in the suppression of bacterial proliferation in the early and chronic phases, and the specific antibody might have a supplementary effect on the defensive action of PMNs in the chronic phase. It is also presumed that the bacteria in the chronic phase of infection are sequestered at sites hardly accessible to PMNs.
Iizawa
Y
Y
Biology Research Laboratories, Takeda Chemical Industries, Ltd., Osaka.
Nishi
T
T
Kondo
M
M
Imada
A
A
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000382:microbiology; D015169:Colony Count, Microbial; D003520:Cyclophosphamide / Q000494:pharmacology*; D004195:Disease Models, Animal; D005260:Female; D007106:Immune Sera / Q000008:administration & dosage* / Q000276:immunology; D007710:Klebsiella Infections / Q000276:immunology* / Q000517:prevention & control; D007711:Klebsiella pneumoniae; D007958:Leukocyte Count; D051379:Mice; D008808:Mice, Inbred CBA; D009504:Neutrophils / Q000276:immunology*; D012141:Respiratory Tract Infections / Q000276:immunology*
D007106:Immune Sera; D003520:Cyclophosphamide