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Complement receptors in neutrophils
1Department of Hematology L-4041, Rigshospitalet, Copenhagen, Denmark.
Critical Reviews in Immunology
|January 1, 1995
Summary
Neutrophils rapidly mobilize secretory vesicles containing complement receptors to their surface upon inflammatory mediator stimulation. This ensures quick upregulation of these receptors, crucial for neutrophil immune responses.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Human neutrophils possess intracellular granules and vesicles.
- These components undergo exocytosis upon stimulation with inflammatory mediators.
- Neutrophil activation involves a hierarchical release of these components.
Purpose of the Study:
- To investigate the role of secretory vesicles in neutrophil activation.
- To identify complement receptors within neutrophil secretory vesicles.
- To understand the transport and surface expression of complement receptors during neutrophil activation.
Main Methods:
- Stimulation of human neutrophils with inflammatory mediators at nanomolar concentrations.
- Analysis of secretory vesicle mobilization and exocytosis.
- Identification and localization of complement receptors (C1qR, CR1, CR3, CR4, C5aR) within neutrophils.
Main Results:
- Secretory vesicles are fully mobilized to the plasma membrane upon stimulation.
- Secretory vesicles transport at least four complement receptors (C1qR, CR1, CR3, CR4) to the neutrophil surface.
- Integrins CR3 and CR4 exhibit dual localization in both secretory vesicles and granules.
- A fifth complement receptor, C5aR, is constitutively present on the plasma membrane.
Conclusions:
- Secretory vesicle mobilization ensures prompt upregulation of complement receptors on neutrophils early in activation.
- The diverse subcellular localization of complement receptors facilitates graded expression in response to stimulation.
- This mechanism is vital for effective neutrophil function in inflammatory responses.