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In vitro biosynthesis of complement protein D by U937 cells
Journal of Immunology (Baltimore, Md. : 1950)
|March 1, 1985
Summary
Human monocyte cells (U937) synthesize and secrete functionally active D protein. This secreted D is antigenically and structurally similar to serum D, indicating its potential role in immune responses.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Preliminary studies indicated that blood monocytes/macrophages secrete antigenic D.
- The U937 cell line, derived from human monocytes, was utilized to investigate D biosynthesis.
Purpose of the Study:
- To investigate the biosynthesis and secretion of antigenic D by U937 cells.
- To characterize the functional activity, kinetics, and molecular properties of D produced by U937 cells.
Main Methods:
- Kinetics of D secretion were measured using radioimmunoassay and hemolytic assay.
- D synthesis was assessed by [35S]methionine labeling and SDS-PAGE analysis.
- Functional activity was confirmed through hemolytic assays and cycloheximide inhibition studies.
Main Results:
- U937 cells synthesized D nearly linearly over a 6-day period.
- Produced D was hemolytically active and showed specific hemolytic activity comparable to serum D.
- SDS-PAGE revealed a main band of approximately 24,000 m.w., confirmed as D, which was antigenically similar to purified D.
Conclusions:
- U937 cells are capable of synthesizing functionally active D.
- The D produced by U937 cells is structurally and antigenically similar to serum D.
- These findings support the role of monocytes/macrophages in D production and secretion.
