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Human polymorphonuclear leukocytes store large amounts of terminal complement components C7 and C6, which may be
A K Høgåsen1, R Würzner, T G Abrahamsen
1Department of Pediatric Research, National Hospital, Oslo, Norway.
Journal of Immunology (Baltimore, Md. : 1950)
|May 1, 1995
Summary
Human polymorphonuclear leukocytes (PMNs) secrete complement factors C7 and C6 more readily than C3. These findings suggest PMNs play a key role in modulating the complement system
Area of Science:
- Immunology
- Complement System Biology
Background:
- The complement system is crucial for innate immunity.
- Polymorphonuclear leukocytes (PMNs) and peripheral blood mononuclear cells (PBMCs) are key immune cells.
- The secretion patterns of complement factors by these cells are not fully understood.
Purpose of the Study:
- To investigate the secretion of complement factors C7, C6, and C3 by human PMNs and PBMCs.
- To determine the cellular source and regulation of complement factor release.
Main Methods:
- Enzyme-linked immunosorbent assay (ELISA) and immunoblotting were used to quantify complement factors.
- Cell cultures of PMNs and PBMCs were stimulated with phorbol 12-myristate 13-acetate (PMA) and unopsonized Candida species.
- Analysis of complement factor content in cell lysates and secreted media.
Main Results:
- PMNs released significantly higher amounts of C7 and C6 compared to C3.
- PBMCs showed a different pattern, with higher C3 release relative to C7 and C6.
- PMA stimulation enhanced complement factor secretion, while Candida species did not.
- PMN complement factor release was independent of de novo protein synthesis.
Conclusions:
- PMNs are a major source of complement factors C7 and C6, potentially more significant than monocytes/macrophages at inflammatory sites.
- PMNs may act as modulators of the complement membrane attack complex.
- Complement components are likely produced by PMNs or their precursors before ex vivo culture.