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Dynamic ca(2+)changes in neutrophil phagosomes A source for intracellular ca(2+)during phagolysosome formation?
H Lundqvist-Gustafsson1, M Gustafsson, C Dahlgren
1Division of Pathology II, Faculty of Health Sciences, Linköping University, Sweden.
Cell Calcium
|October 3, 2000
Summary
Phagosomes, the cell compartments that engulf microbes, actively release calcium ions (Ca2+) into the cytosol. This localized calcium rise is crucial for neutrophil-mediated microbial elimination and phagosome processing.
Area of Science:
- Cell Biology
- Immunology
- Microbiology
Background:
- Cytosolic calcium (Ca2+) concentration is vital for phagolysosomal formation and microbial elimination by neutrophils.
- Calcium increases can originate from intracellular stores or passive entry into the phagosome.
Purpose of the Study:
- To investigate intraphagosomal Ca2+ dynamics in human neutrophils during phagocytosis.
- To determine the source and role of Ca2+ in phagosome processing.
Main Methods:
- Human neutrophils were used to phagocytose serum opsonized Fura-2-conjugated zymosan particles.
- Digital image processing microspectrofluorometry measured intraphagosomal Ca2+ changes.
- The effect of econazole on plasma membrane Ca2+ channels was assessed.
Main Results:
- A rapid decrease in intraphagosomal Ca2+ to nanomolar levels was observed after phagosomal closure.
- Blocking plasma membrane Ca2+ channels with econazole prevented this Ca2+ decrease.
- Fura-2 zymosan fluorescence remained stable, confirming its integrity during phagocytosis.
Conclusions:
- Phagosomes serve as a source of Ca2+ ions.
- Ca2+ ions exit phagosomes into the cytosol via phagosomal membrane channels.
- This efflux creates a localized cytosolic Ca2+ rise essential for phagosome maturation and microbial clearance.