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Query: UMLS:C0023241 (Legionella)
 6,990 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The interaction of L. pneumophila serogroup 1 sonic extract with human polymorphonuclear neutrophils and monocytes was studied in an in vitro chemotaxis assay. The sonicate showed heat-stable chemotactic activity towards neutrophils and monocytes. It also exhibited cytotoxicity for neutrophils but not for monocytes. Incubation and pretreatment with the sonicate at apparently non-toxic concentration resulted in inhibition of the chemotactic response of neutrophils to various chemoattractants while monocyte chemotaxis was unaffected. The inhibitory activity was reduced to one half by heat treatment of the sonicate. High endotoxic activity was demonstrated in both heated and non-heated extract. Only two antigens (nos 1 and 61) were identified in the sonicate exposed to 121 degrees C for 1 h. It is therefore suggested that the lipopolysaccharide (no. 61) of L. pneumophila could contribute to the chemotactic activity. The adverse effects exerted by L. pneumophila on neutrophils may be one of the mechanisms by which Legionella bacteria resist the normal phagocytic host defenses.
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PMID:Effects of Legionella pneumophila sonicate on human neutrophil granulocyte and monocyte chemotaxis. 310 Mar 4

Over five years 18 strains of Legionella pneumophila serogroup 6 were isolated in Amsterdam from the hot water supply in three hospitals and from one patient. Immunodiffusion and immunoblot procedures showed that these strains were identical. Profiles of isolated lipopolysaccharides from the 18 strains and the reference serogroup 6 strain were visualised in polyacrylamide gels stained with silver. Four strains from hospital A, isolated in 1982, 1984, and 1985 displayed similar lipopolysaccharide profiles which were different in relative mobility from those of hospitals B and C. Those from hospital B (12 strains isolated in 1983 and 1986) and C (one strain) were similar in relative mobility but different in colour. The strain from a patient with acquired immune deficiency syndrome (AIDS) in hospital A displayed a lipopolysaccharide profile characteristic of hospital A. These reproducible profiles were all different in relative mobility from the reference serogroup 6 strain. They can be used as a marker system in epidemiological surveys of serologically identical serogroup 6 strains. Lipopolysaccharide patterns from strains isolated throughout the years in the same hospital were similar. This suggests an outgrowth from organisms inhabiting the plumbing system rather than reseeding from the Amsterdam mains supply.
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PMID:Differences in lipopolysaccharide profiles of serologically identical Legionella pneumophila serogroup 6 strains. 313 16

A genomic library of Legionella pneumophila was constructed by inserting L. pneumophila knoxville-1 strain (LPK-1) chromosome fragments into cosmid vector pHC79. Screening of the library with antibodies directed against a major outer membrane protein/lipopolysaccharide complex from LPK-1 resulted in the identification of six clones that reacted with the antiserum. Western blot analysis indicated that a 19,000 dalton (19 kDa) component was the reactive antigen in all of the clones. Western blot analysis of outer membranes from L. pneumophila serogroups and other Legionella species revealed that the cloned 19 kDa antigen was common to all serogroups and all but one of the five other Legionella species examined. One of the 19 kDa expressing clones was used as an immunoabsorbent to recover antibody to the 19 kDa antigen thus confirming the surface localization of this L. pneumophila antigen in E. coli.
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PMID:Cloning and expression of a common Legionella outer membrane antigen in Escherichia coli. 333 97

Outer membranes were isolated from eight serogroups of L. pneumophila and five other Legionella species. The protein composition of the membranes was characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A single, disulfide stabilized protein with a molecular size of 29,000 to 30,000 daltons was found to be the major outer membrane protein (MOMP) of all the serogroups. The equivalent of the L. pneumophila MOMP was not observed in any of the other Legionella species examined. Silver staining of sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels revealed distinctive patterns for each serogroup and other Legionella species that were not observed by staining with Coomassie blue and may result from the presence of lipopolysaccharide in the membrane preparations. The MOMP from serogroup 1 was isolated by exposing crude peptidoglycan to detergent in the presence of heat and reducing agent and was found to be tightly associated with lipopolysaccharide. Antibodies to this complex were used to probe the outer membranes of the remaining, L. pneumophila serogroups and other Legionella species by Western blotting. Serogroup 1 anti-MOMP antibodies were found to react with the MOMP from the remaining seven serogroups examined, whereas antibodies directed against the lipopolysaccharide of serogroup 1 only reacted with lipopolysaccharide from two of the remaining seven serogroups.
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PMID:Outer membrane proteins from Legionella pneumophila serogroups and other Legionella species. 351 Jan 78

Legionella pneumophila, the etiologic agent of Legionnaires' disease, is phagocytized in an unusual way and multiplies in human mononuclear phagocytes in a novel phagosome. As a first step toward understanding these L. pneumophila-phagocyte interactions, we have studied the envelope of L. pneumophila Philadelphia 1 strain. We isolated cell envelopes by treating whole bacterial cells with lysozyme and EDTA to convert them to spheroplasts, then lysing the spheroplasts osmotically or sonically. We resolved the cell envelopes into two membrane fractions by isopycnic centrifugation. We localized NADH oxidase to the fraction of buoyant density 1.145, which we designated cytoplasmic membrane, and lipopolysaccharide (LPS) to the fraction of density 1.222, which we designated outer membrane. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed that the L. pneumophila outer membrane contains a single major protein species migrating at 28,000 mol wt; this is the major protein of the bacterium. The cytoplasmic membrane also contains a single major protein species migrating at 65,000 mol wt. Surface iodination of the bacteria and agglutination and immunofluorescence studies with rabbit antibody produced against the purified major outer membrane protein (MOMP) revealed that this protein is exposed at the cell surface. We isolated LPS from L. pneumophila membranes by SDS-EDTA treatment. The pattern obtained by subjecting the LPS to SDS-PAGE and staining the gel with silver nitrate suggests that L. pneumophila LPS might be atypical. We studied patient serologic responses to cell envelope components of L. pneumophila Philadelphia 1, a serogroup 1 organism. Sera from patients with evidence of infection with serogroup 1 L. pneumophila contained large amounts of antibody to this strain. Few of these antibodies recognized the MOMP of L. pneumophila. In contrast, greater than 98% of these antibodies were directed against the LPS. This indicates that LPS is the dominant serogroup antigen and the major antigen responsible for the reactivity of patient sera in the indirect fluorescent antibody assay, currently the principal diagnostic assay for Legionella infection.
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PMID:Isolation and characterization of the cytoplasmic and outer membranes of the Legionnaires' disease bacterium (Legionella pneumophila). 388 79

Serogroup-specific antigen was extracted from a number of Legionella pneumophila strains and compared with phenol-water extracted lipopolysaccharide on the basis of gel filtration, chemical analysis, SDS-PAGE and reaction with serogroup-specific antibody in immunoblots. Serogroup specificity is apparently borne by the O side-chains of the lipopolysaccharide, which, although smooth in type, partitions in the phenol phase. For four serogroup 1 strains tested, there was no qualitative correlation between O side-chain length and pulmonary virulence for guinea-pigs.
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PMID:The relationship between the serogroup antigen and lipopolysaccharide of Legionella pneumophila. 395 Mar 95

The antigens of the six serogroups of Legionella pneumophila were compared by two-dimensional (crossed) immunoelectrophoresis by using rabbit antisera to serogroups 1, 2, 3 and 4. The close relationship among the serogroups was shown by the fact that 27 of the 31 antigens demonstrated so far were common. However, distinctive group-specific antigens with slow electrophoretic mobility were observed for serogroups 1, 2, 3, and 4. When intact serogroup 1 organisms were extracted with EDTA, the group-specific antigen was recovered in a virtually pure form. The group-specific antigen was pronase resistant, heat stable, and amphiphilic and had a surface location, all of which are properties suggestive of lipopolysaccharide. L. pneumophila shared four to five antigens with Tatlockia micdadei (Legionella micdadei). The large number of common antigens in the serogroups of L. pneumophila has important implications for the specific detection of antigens and antibodies by fluorescent and other tagged antibody methods.
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PMID:Antigenic analysis of Legionella pneumophila and Tatlockia micdadei (Legionella micdadei) by two-dimensional (crossed) immunoelectrophoresis. 617 28

Incubation of normal mouse resident peritoneal cell suspensions rich in macrophages with Legionella pneumophila whole cell vaccine or soluble preparations thereof resulted in marked inhibition of the ability of the cells to spread on glass surfaces during a 24-h period. This inhibition, however, was transient in that by day 2 to 3 after culture initiation only partial inhibition was evident, and by day 4 to 5 thereafter most of the treated macrophage cultures showed normal spreading activity. Suppression of macrophage spreading was evident not only with intact Legionella preparations and the sonic extract but also with a lipopolysaccharide-rich somatic antigen preparation and flagella. The suppressive effects of Legionella preparations on a functional activity of normal macrophages in vitro indicate that these bacteria may have a detrimental effect on an important activity of cells involved in the immune defense system.
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PMID:Legionella pneumophila-induced suppression of macrophage spreading in vitro. 661 71

The pathogenetic mechanism and virulence factors involved in infections and Legionella are little understood. In vitro studies by thin-section and scanning electron microscopy show that legionella organisms attach to mammalian cells in culture, are taken into cytoplasmic vacuoles lined with ribosomes and replicate, probably utilising cell-derived amino acids. The presence of pili (fimbriae), lipopolysaccharide and protein structures at the bacterial surfaces is no doubt related to the initial adhesion to cell surface receptors. Motility through flagella and toxin production add to the potential invasiveness of these bacteria. Intracellular longterm survival and replication in alveolar macrophages affords a mechanism for increasing bacterial infectivity while avoiding the host's immune system, amplifying microbial pathogenicity.
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PMID:The role of structure and invasiveness on the pathogenicity of Legionella. 663 28

Injection of Legionella pneumophila antigen, either killed vaccine or soluble sonicate thereof, resulted in an enhanced antibody response by mouse spleen cells to sheep erythrocytes as determined by the hemolytic plaque assay. Enhancement was dose dependent and reached a peak response at a concentration of 10(7) bacteria or 50 micrograms of sonicate per animal. Larger doses of antigen were less stimulatory or even depressed the antibody response. Similar enhancement of antibody formation by normal spleen cell cultures to sheep erythrocytes in vitro occurred in the presence of graded amounts of L. pneumophila vaccine or sonicate. In addition, the L. pneumophila antigen stimulated enhanced background antibody formation in vitro in the absence of sheep erythrocytes or specific antigen. It appeared likely that the immunoenhancing activity of the L. pneumophila extract may be unrelated to the presence of lipopolysaccharide since boiling the antigen preparation eliminated much of the antibody-enhancing properties of the extract. A large-molecular-weight surface component from L. pneumophila was also immunomodulatory in vitro. Immunostimulation appeared to be related to effects on macrophages since adherent spleen cell populations rich in macrophages, when derived from spleen cell suspensions incubated with L. pneumophila antigen in vitro, stimulated enhanced antibody formation by normal mouse spleen cells in coculture experiments. Further investigations concerning the mechanism of immunomodulation by L. pneumophila antigen in vivo and in vitro appear to be warranted.
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PMID:Immunostimulation by Legionella pneumophila antigen preparations in vivo and in vitro. 669 Apr 9


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