The Journal of Medical Microbiology, Vol 28, Issue 2 101-108, Copyright © 1989 by Society for General Microbiology
Antibody-independent protection against Pseudomonas aeruginosa infection in mice after treatment with a homologous strain vaccine
T. Fujimura, T. Suzuki, M. Mitsuyama, H. Saito and K. Nomoto
Department of Veterinary Microbiology, School of Veterinary Medicine, Kitasato University, Aomori, Japan.
Formalin-killed cells of Pseudomonas aeruginosa strain M-24 elicited an
antibody-independent protective effect against P. aeruginosa infection in
mice. The effect was observed as early as 6 h after administration and 100%
protection was obtained by 48 h. The protective effect could not be
attributed to the production of specific antibody. In M-24-treated mice,
the bacteria in the peritoneal cavity, blood and liver were eliminated 12 h
after P. aeruginosa infection. This suggested that the protective effect
was due to enhanced bacterial elimination. The percentage of macrophages in
the peritoneal cavity was increased after M-24 administration. Furthermore,
the enhanced bacterial elimination was abrogated by treatment of mice with
60Co-irradiation or carrageenan. These findings suggest the involvement of
macrophages in the enhanced bacterial elimination observed. The
chemiluminescence of peritoneal exudate cells from M-24-treated mice was
markedly increased when compared with that of cells from untreated mice.
The ability to kill P. aeruginosa in vitro was also greater in macrophages
from mice treated with killed M-24 than in cells from
proteose-peptone-treated mice. The M-24-treated mice showed enhanced
nonspecific protection against infection with lethal doses of P.
aeruginosa, Escherichia coli or Listeria monocytogenes. However,
susceptibility to LPS in mice was not increased by M-24 treatment. These
results suggest that macrophage activation without increasing LPS
susceptibility was responsible for the antibody-independent protection
induced by killed M-24.
