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Diffusible suppressor factor from splenic macrophages in murine plasmacytoma
Clinical and Experimental Immunology
|July 1, 1984
Summary
Splenic macrophages produce a diffusible suppressor factor (DSF) that inhibits immune responses in mice with plasmacytoma. This non-immunoglobulin protein is crucial for tumor progression and requires continuous synthesis.
Area of Science:
- Immunology
- Cancer Biology
- Cell Biology
Background:
- Splenic macrophages (M phi) in tumor-bearing mice exhibit immunosuppressive properties.
- This immunosuppression is mediated by a diffusible factor (DSF).
Purpose of the Study:
- To characterize the nature and production of the diffusible suppressor factor (DSF).
- To elucidate the molecular properties and synthesis requirements of DSF.
Main Methods:
- Biochemical analysis of DSF (non-dialyzable, heat-sensitive, trypsin-sensitive).
- Ligand binding assays using myeloma proteins and specific ligands (dinitrophenyl L-lysine, dextran S).
- Immunological assays with anti-idiotypic and anti-isotypic antibodies.
- Inhibition studies using metabolic inhibitors of RNA, protein, and DNA synthesis.
Main Results:
- DSF binds to ligands specific for corresponding myeloma proteins.
- DSF cross-reacts with anti-idiotypic antibodies but not anti-isotypic antibodies to mouse immunoglobulins (Ig).
- DSF production is blocked by inhibitors of RNA and protein synthesis, but not DNA synthesis, indicating it is a non-Ig protein.
Conclusions:
- DSF is a novel non-Ig protein produced by splenic suppressor M phi.
- DSF possesses structural similarities to myeloma idiotype.
- Continuous RNA and protein synthesis are essential for DSF elaboration by M phi.