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Microfilament-associated degranulation of sensitized guinea-pig lung mast cells
1Department of Pharmacology, Faculty of Pharmaceutical Sciences, Okayama University, Japan.
Abstract:
When sensitized guinea-pig lung mast cells were exposed to antigen, granules were pushed out on to the cell surface. Subsequently, thin filaments, some extending as long as 15 microns, were projected radially with the extruded granules. The latter became swollen in the extracellular medium and the elongated filaments became shorter, until, within 7-8 min, the granules were reincorporated into the cytoplasm. The time course of morphological changes corresponded approximately to that of changes in the intracellular Ca2+ concentrations. The filaments connecting the extruded granules to the cell surface were stained with rhodamine-phalloidin, indicating that they consisted mainly of actin.
Insights
Guinea-pig mast cells extrude granules upon antigen exposure, forming actin filaments. These granules are later reincorporated into the cell, mirroring calcium level changes.
Area of Science:
- Cell Biology
- Immunology
- Biochemistry
Background:
- Mast cells play a crucial role in allergic reactions.
- Granule exocytosis is a key mechanism for mast cell degranulation.
Purpose of the Study:
- To investigate the dynamic morphological changes of mast cells during antigen-induced degranulation.
- To elucidate the role of actin filaments in granule extrusion and reuptake.
Main Methods:
- Sensitized guinea-pig lung mast cells were exposed to antigen.
- Morphological changes were observed using microscopy.
- Intracellular calcium concentrations were monitored.
- Actin filaments were visualized using rhodamine-phalloidin staining.
Main Results:
- Antigen exposure triggered granule extrusion from mast cells.
- Long actin filaments (up to 15 microns) extended with extruded granules.
- Extruded granules were reincorporated into the cytoplasm within 7-8 minutes.
- The timing of morphological changes correlated with intracellular calcium fluctuations.
- Filaments connecting granules to the cell surface were identified as primarily actin.
Conclusions:
- Mast cells exhibit dynamic actin-dependent mechanisms for granule extrusion and reuptake.
- Actin filament dynamics are closely linked to calcium signaling during mast cell degranulation.