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Suppressive factor of tumour origin against macrophage phagocytosis of Staphylococcus aureus
Abstract:
Peritoneal macrophages from Sarcoma-180-bearing mice against Staphylococcus aureus were studied to determine the in vitro phagocytic capacities. When the phagocytic system was opsonized with normal mouse serum, macrophage phagocytic activity increased markedly soon after tumour graft and then returned to normal. A new antiphagocytic factor was detected in the serum of tumour-bearers soon after tumour implantation. This factor was of tumour origin, stable even at a temperature of 56 degrees C for 30 min and non-dialysable. Peptone-starch-induced macrophages were less sensitive to the factor than their unstimulated counterpart.
Insights
Tumor growth in mice releases an antiphagocytic factor that impairs macrophage defense against Staphylococcus aureus. This tumor-derived factor is heat-stable and affects macrophage function.
Area of Science:
- Immunology
- Cancer Biology
- Microbiology
Background:
- Peritoneal macrophages play a crucial role in host defense against bacterial infections like Staphylococcus aureus.
- Tumorigenesis can significantly alter the host immune environment, potentially impacting macrophage function.
- Understanding these alterations is vital for developing effective cancer and infection therapies.
Purpose of the Study:
- To investigate the in vitro phagocytic capacities of peritoneal macrophages from Sarcoma-180-bearing mice.
- To identify and characterize any factors in tumor-bearer serum that influence macrophage phagocytosis.
- To assess the impact of a novel antiphagocytic factor on macrophage sensitivity.
Main Methods:
- Isolation of peritoneal macrophages from Sarcoma-180-bearing mice and control mice.
- Assessment of macrophage phagocytic activity against Staphylococcus aureus in vitro.
- Opsonization of the phagocytic system with normal mouse serum.
- Detection and characterization of antiphagocytic factors in tumor-bearer serum (stability, dialyzability).
- Comparison of sensitivity to the antiphagocytic factor between unstimulated and peptone-starch-induced macrophages.
Main Results:
- Macrophage phagocytic activity initially increased post-tumor graft but returned to normal levels.
- A novel, heat-stable (56°C for 30 min), non-dialyzable antiphagocytic factor was detected in tumor-bearer serum.
- This factor originated from the tumor and impaired macrophage phagocytosis.
- Peptone-starch-induced macrophages exhibited reduced sensitivity to this antiphagocytic factor compared to unstimulated macrophages.
Conclusions:
- Sarcoma-180 tumor implantation in mice leads to the production of a serum-borne antiphagocytic factor.
- This tumor-derived factor compromises the host's ability to clear Staphylococcus aureus via peritoneal macrophages.
- Macrophage activation state influences their susceptibility to this novel immunosuppressive factor, suggesting potential therapeutic targets.