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A small molecular weight peptide from P815 mastocytoma cells induces macrophage cytotoxicity
Abstract:
In a previous article we have shown the presence of a "factor" in the cell free exudates of intraperitoneally growing P815 mastocytoma cells as well as in cell-free tumor cell extracts. This "factor" is able to induce nonspecific macrophage cytotoxicity against tumor target cells. The "factor" was sensitive to heating at 100 degree C for 1 min, destroyed by pronase treatment, and dialyzable. On the other hand, the "factor" was not removed by centrifugation (25,000 x g), and was resistant to chloroform extraction, ultraviolet irradiation, heating at 56 degree C (for 20 min), or RNAase treatment. Sephadex gel fractionation of the mastocytoma exudate showed that the "factor" has an approximate molecular weight of 650-700 daltons. Normal peritoneal macrophages incubated with an extract of murine mast cells, purified histamine or serotonin did not show detectable cytotoxicity against tumor cells. The results of our experiments suggest that the effect of the P815 cell-free exudate and tumor cell extract is due to a dialyzable small molecular weight peptide.
Insights
Researchers identified a small peptide factor in P815 mastocytoma cells that enhances macrophage cytotoxicity against tumor cells. This factor, with a molecular weight of 650-700 daltons, shows promise in cancer research.
Area of Science:
- Immunology
- Cancer Biology
- Biochemistry
Background:
- Previous studies indicated a "factor" in P815 mastocytoma cells induces macrophage cytotoxicity.
- This factor was present in cell-free exudates and tumor cell extracts.
Purpose of the Study:
- To characterize the nature of the factor responsible for inducing macrophage cytotoxicity.
- To determine the physicochemical properties and molecular weight of the active factor.
Main Methods:
- Sensitivity to heat, pronase, and RNAase treatment.
- Resistance to chloroform extraction and UV irradiation.
- Sephadex gel fractionation to estimate molecular weight.
Main Results:
- The factor was dialyzable, heat-sensitive (100°C for 1 min), and destroyed by pronase.
- It was resistant to chloroform, UV, 56°C heat, and RNAase.
- Molecular weight was estimated at 650-700 daltons, suggesting a peptide.
Conclusions:
- The observed nonspecific macrophage cytotoxicity is attributed to a small, dialyzable peptide.
- This peptide factor from P815 mastocytoma cells represents a potential target for cancer therapy research.
