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Macrophage stimulating protein: purification, partial amino acid sequence, and cellular activity
A Skeel1, T Yoshimura, S D Showalter
1Immunopathology Section, National Cancer Institute, Frederick, Maryland 21702.
The Journal of Experimental Medicine
|May 1, 1991
Summary
Macrophage stimulating protein (MSP) was purified from human plasma and found to be a novel protein. MSP activates macrophages, enhancing their response to chemoattractants and promoting phagocytosis.
Area of Science:
- Immunology
- Biochemistry
- Cell Biology
Background:
- Macrophage stimulating protein (MSP) is a key regulator of immune responses.
- Understanding MSP's structure and function is crucial for immune system research.
Purpose of the Study:
- To purify and characterize Macrophage stimulating protein (MSP) from human blood plasma.
- To investigate the biological activities of purified MSP on macrophages.
Main Methods:
- Immunoaffinity and ion exchange chromatography for MSP purification.
- SDS-PAGE and Western blotting for molecular mass determination.
- Macrophage functional assays to assess MSP's biological activity.
Main Results:
- MSP was purified to homogeneity with a molecular mass of 70 kD, existing as a disulfide-linked two-chain structure.
- Sequence analysis revealed MSP is a novel protein with partial homology to the prothrombin family.
- Purified MSP activated mouse macrophages, enhancing chemoattractant responses, inducing morphological changes, and promoting phagocytosis via CR1 and C5a receptors.
Conclusions:
- Macrophage stimulating protein (MSP) is a newly identified human plasma protein.
- MSP directly activates macrophages, modulating their immune functions through specific receptor pathways.