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Alternative complement pathway-dependent ingestion of fluolite particles by human granulocytes
Journal of Immunology (Baltimore, Md. : 1950)
|July 1, 1981
Summary
Human granulocytes ingest fluorescent particles via complement activation. This process, dependent on the alternative pathway, can be quantified using this method.
Area of Science:
- Immunology
- Cell Biology
Background:
- Phagocytosis is a crucial cellular process for immune defense.
- Complement system activation plays a vital role in opsonization and phagocytosis.
Purpose of the Study:
- To investigate the role of the complement system in the phagocytosis of fluorescent particles by human granulocytes.
- To establish a quantitative functional assay for the alternative pathway of complement activation.
Main Methods:
- Human granulocytes were incubated with fluorescent particles (Fluolite) in normal human serum (NHS).
- Ingestion was assessed by fluorescent microscopy.
- Complement components and inhibitors were used to elucidate the mechanism of phagocytosis.
Main Results:
- Particle ingestion by granulocytes required fresh NHS and was dependent on complement activation.
- Phagocytosis was inhibited by heat inactivation of serum or the presence of EDTA, indicating complement involvement.
- Deficiency in C3 or C3b inactivator abolished ingestion, while C3 supplementation restored it.
- The alternative pathway of complement activation was identified as the primary mediator of opsonization.
Conclusions:
- Opsonization of fluorescent particles by human granulocytes is mediated by the alternative pathway of complement activation.
- This system provides a simple and quantitative functional assay for measuring alternative pathway activity.