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Updated: Aug 10, 2026
Pseudomonas aeruginosa Induced Lung Injury Model
Published on: October 29, 2014
The effect of Pseudomonas aeruginosa cytotoxin and toxin A on human polymorphonuclear leukocytes
M B Bishop1, A L Baltch, L A Hill
1Department of Pathology, VA Medical Center, Albany, New York 12208.
Abstract:
After exposure to cytotoxin or toxin A of Pseudomonas aeruginosa, the ultrastructure of resting and phagocytosing human polymorphonuclear leukocytes (PMNL) and of cells of P. aeruginosa strain 1348A was studied by transmission (TEM) and scanning (SEM) electronmicroscopy, and by light microscopy (LM) after histochemical staining of cytoplasmic granules. Cytotoxin caused marked clumping and destruction of PMNL, pyknotic nuclear changes with bleb formation, and release of cytoplasmic granules; phagocytosis was markedly diminished. In contrast, after exposure to toxin A, PMNL phagocytosed actively, but their cytoplasmic pseudopodia were markedly irregular and their nuclei pyknotic. Colloidal-gold-labelled cytotoxin showed an affinity for the cytoplasmic membranes, nuclei and granules of PMNL. Cytotoxin had no apparent effect on cells of P. aeruginosa strain 1348A but there was polar separation of the cytoplasmic membrane in bacteria exposed to toxin A. Cytotoxin and toxin A appear to be important in the pathogenesis of infections caused by P. aeruginosa.
Insights
Pseudomonas aeruginosa cytotoxin destroys human white blood cells (PMNL), impairing phagocytosis. Toxin A also affects PMNL and bacteria, suggesting both are key in P. aeruginosa infections.
Area of Science:
- Microbiology
- Immunology
- Cell Biology
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen.
- Bacterial toxins play a crucial role in infectious disease pathogenesis.
- Human polymorphonuclear leukocytes (PMNL) are critical immune cells involved in pathogen clearance.
Purpose of the Study:
- To investigate the ultrastructural effects of Pseudomonas aeruginosa cytotoxin and Toxin A on human PMNL.
- To examine the impact of these toxins on bacterial cell morphology.
- To elucidate the role of cytotoxin and Toxin A in P. aeruginosa pathogenesis.
Main Methods:
- Transmission and scanning electron microscopy (TEM/SEM) were used to study PMNL and bacterial ultrastructure.
- Light microscopy (LM) with histochemical staining assessed cytoplasmic granules.
- Colloidal-gold labeling tracked cytotoxin localization within PMNL.
Main Results:
- Cytotoxin induced PMNL clumping, destruction, nuclear changes, granule release, and reduced phagocytosis.
- Toxin A exposure led to active PMNL phagocytosis but with irregular pseudopodia and nuclear changes.
- Cytotoxin did not affect P. aeruginosa strain 1348A, while Toxin A caused polar separation of bacterial cytoplasmic membranes.
Conclusions:
- Cytotoxin and Toxin A exhibit distinct effects on human PMNL.
- Both toxins appear to play significant roles in the pathogenesis of P. aeruginosa infections.
- Understanding toxin-host interactions is vital for combating P. aeruginosa.
