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Cytotoxic effects of leukocidin from Pseudomonas aeruginosa on polymorphonuclear leukocytes from cattle
Abstract:
The cytotoxic action of leukocidin from Pseudomonas aeruginosa was studied in vitro by following the release of various intracellular markers from polymorphonuclear leukocytes from cattle (PMLC). Low-molecular markers (K+, 86Rb+, glucose) were lost from PMLC within 1 to 2 min after the addition of leukocytes. The release of high-molecular-weight indicators (51Cr, bound to intracellular protein; lactate dehydrogenase) occurred only after swelling of the cells, leading to an increased permeability of the plasma membrane. Calcium ions stimulated the leakage of granule enzymes but retarded or inhibited the release of cytoplasmic markers. At 4 C, leukocytes were unaffected by the toxin. Leukocidin, bound at 4 C to leukocytes and treated with antiserum against leukocidin, did not damage the cells upon increasing the incubation temperature to 37 C.
Insights
Pseudomonas aeruginosa leukocidin causes rapid cell damage by increasing plasma membrane permeability in bovine polymorphonuclear leukocytes (PMLC). Calcium ions influence marker release, and low temperatures prevent toxin binding and cell damage.
Area of Science:
- Microbiology
- Immunology
- Cell Biology
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen known to produce toxins.
- Leukocidins are a class of toxins that can damage host immune cells.
- Understanding leukocidin's mechanism is crucial for combating bacterial infections.
Purpose of the Study:
- To investigate the in vitro cytotoxic effects of Pseudomonas aeruginosa leukocidin on bovine polymorphonuclear leukocytes (PMLC).
- To characterize the release patterns of intracellular markers from PMLC upon leukocidin exposure.
- To determine the role of temperature and calcium ions in the cytotoxic mechanism.
Main Methods:
- In vitro study using bovine polymorphonuclear leukocytes (PMLC).
- Monitoring the release of low-molecular (K+, 86Rb+, glucose) and high-molecular (51Cr, lactate dehydrogenase) intracellular markers.
- Incubation at different temperatures (4°C and 37°C) and presence/absence of calcium ions.
Main Results:
- Leukocidin rapidly induced the release of low-molecular markers within 1-2 minutes.
- High-molecular markers were released after cell swelling and increased plasma membrane permeability.
- Calcium ions promoted granule enzyme leakage but inhibited cytoplasmic marker release.
- Low temperatures (4°C) prevented leukocidin binding and subsequent cell damage, even after warming.
Conclusions:
- Pseudomonas aeruginosa leukocidin induces cell damage through a temperature-dependent mechanism affecting plasma membrane permeability.
- Calcium ions modulate the release of different intracellular components, suggesting distinct pathways.
- The study provides insights into the molecular mechanisms of leukocidin cytotoxicity against immune cells.