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Murine polymorphonuclear leukocytes synthesize and secrete the third component and factor B of complement
1Research Institute for Tuberculosis and Cancer, Tohoku University, Sendai, Japan.
International Immunology
|April 1, 1991
Summary
Polymorphonuclear leukocytes (PMNs) synthesize and secrete complement proteins C3 and factor B. This groundbreaking discovery reveals a new source of complement factors at inflammatory sites.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- Complement proteins are crucial for immune responses.
- Traditionally, hepatocytes and macrophages are known complement producers.
- Polymorphonuclear leukocytes (PMNs) were not previously recognized as secretors of complement.
Purpose of the Study:
- To investigate the potential synthesis and secretion of complement proteins by PMNs.
- To characterize complement components produced by PMNs.
Main Methods:
- Murine peritoneal exudate PMNs were elicited using OK432.
- [35S]methionine incorporation and immunoprecipitation were used to detect protein synthesis.
- ELISA, flow cytometry, and immunoperoxidase staining were employed to confirm complement presence.
Main Results:
- PMNs were demonstrated to synthesize and secrete complement C3 and factor B.
- The synthesized C3 and factor B were antigenically and physically identical to those from macrophages.
- Culture supernatants of PMNs (macrophage-free) contained C3 antigen, and intracellular C3 was detected.
Conclusions:
- This study establishes PMNs as a novel source of complement proteins.
- The findings necessitate re-evaluation of complement's role in extravascular inflammatory processes.
- Further research is required to elucidate the functional significance of PMN-derived complement.