Dynamic ca(2+)changes in neutrophil phagosomes A source for intracellular ca(2+)during phagolysosome formation?
An increase in cytosolic Ca(2+)concentration periphagosomally is critical for phagolysosomal formation and neutrophil elimination of microbes. The Ca(2+)increase could be achieved through release of Ca(2+)from mobilized intracellular stores. Alternatively, Ca(2+)that passively enter the phagosome during phagocytosis could be provided by the phagosome. Intraphagosomal Ca(2+)changes in single human neutrophils was measured during phagocytosis of serum opsonized Fura-2-conjugated zymosan particles, using a digital image processing system for microspectrofluorometry. A decrease in phagosomal Ca(2+)down to nanomolar concentrations was seen within minutes following phagosomal closure. Blockage of plasma membrane Ca(2+)channels by econazole abolished this decrease. The fluorescence properties of Fura-2 zymosan were retained after phagocytosis and stable to pH changes, reactive oxygen species, and proteolytic enzymes. We suggest that Ca(2+)ions present in the phagosome enter the cell cytosol through Ca(2+)channels in the phagosomal membrane, achieving a localized Ca(2+)rise that is important for phagosome processing.
Lundqvist-Gustafsson
H
H
Division of Pathology II, Faculty of Health Sciences, Linköping University, Sweden.
Gustafsson
M
M
Dahlgren
C
C
D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002458:Cell Fractionation; D003594:Cytoplasmic Granules / Q000378:metabolism; D005453:Fluorescence; D016257:Fura-2; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000378:metabolism; D018715:Microscopy, Video / Q000379:methods; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D010472:Perchlorates / Q000494:pharmacology; D010588:Phagosomes / Q000378:metabolism* / Q000648:ultrastructure; D015054:Zymosan / Q000378:metabolism
D015220:Calcium Channels; D010472:Perchlorates; D015054:Zymosan; D006861:Hydrogen Peroxide; D002118:Calcium; D016257:Fura-2