Kansenshogaku Zasshi
Online ISSN : 1884-569X
Print ISSN : 0387-5911
ISSN-L : 0387-5911
Interaction of Legionella pneumophila with Human Phagocytes
Atsushi SAITOAkimitsu TOMONAGAJun-ichi KADOTAKazuhito HIRATANIKiyoyasu FUKUSHIMAKenji MORIYoshiteru SHIGENOShigeru KOHNOMasaki HIROTAKohei HARAKazunori TOMONOKeizo YAMAGUCHIYoshikazu ISHIIMasataka ICHIKAWAKunio TAKANO
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1987 Volume 61 Issue 12 Pages 1429-1442

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Abstract

In this study, we have examined the interaction between Legionella pneumophila serogroup 1 (80-045 strain), and human polymorphonuclear leukocytes (PMNs) and monocytes in vitro.
With complement alone or antibody alone, few PMN or monocytes ingested L. pneumophila. Effective phagocytosis of PMNs and monocytes against L. pneumophila was observed only in the presence of both antibody and complement. However, L. pneumophila was not killed by PMN and monocytes, and these bacteria, even when incubated with antibody and complement, were only partially susceptible to killing of PMNs. Virulent guinea pig-through L. pneumophila (virulent L. p.) were more resistant than avirulent agar-grown L. pneumophila (avirulent L. p).
Superoxide production from PMN and monocytes, which was observed when these cells phagocytosed E. coli, was not detected in phagocytosis of L. pneumophila. In the case of virulent L. p., superoxide production from phagocytic cells could not be found even with increased ratios of bacteria to cells and addition of antibody and in avirulent L. p., a little increase of superoxide production was observed only when the ratio of bacteria to cells was the highest.
By electron microscopy of PMN ingested virulent L. p., avirulent L. p. or E. coli in the presence of both antibody and complement, all bacteria were found in the phagosome, and none were found free in the cytoplasm. The volume of the phagosome containing E. coli or avirulent L. p. was often large relative to the volume of the bacteria within it. These phagosomes frequently had more than one organism and were closely surrounded by multivesicular types of lysosomes.
On the other hand, phagosomes containing virulent L. p. were not large and nearly all of these phagosomes had a single bacterium. Around these phagosomes, mitochondria and various types of lysosomes were observed. The findings which suggested fusion of lysosomes with phagosomes were observed often in E. coli, less often in avirulent L. p. and very rarely in virulent L. p.
As stated above, L. pneumophila has some escape mechanisms from the killing system of the phagocytes and the details of these mechanisms should be evaluated in the future.

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© The Japansese Association for Infectious Diseases
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