Related Experiment Videos
Macrophage-activating factor extracted from mycoplasmas
Abstract:
Mycoplasmas (M. gallisepticum, chicken mycoplasmas), in concert with interferon gamma (IFN gamma), were effective in activating macrophages (M theta) to be tumoricidal. The M theta-activating capacity of mycoplasmas was maintained after treatment with heat. 0.1 M NaOH, 1 M HCl, or trypsin. M theta-activating factor was extracted from mycoplasmas with chloroform/methanol and water (Mf-B). Mf-B was also effective in activating M theta in the presence of IFN gamma. The threshold dose of Mf-B for M theta of ordinary C3H/He mice and that for those of C3H/HeJ mice, the latter being known to be low responders to bacterial lipopolysaccharide, were actually the same. This seems to indicate that the effectiveness of Mf-B was not attributable to possibly contaminating lipopolysaccharides, and that the pathway of activity of Mf-B is different from that of lipopolysaccharides. Since the M theta-activating principle was only a very small part of Mf-B, we have not yet succeeded in identifying it, but there was no evidence that it was protein, nucleic acid, sugar, or lipid. The cytotoxicity of M theta activated by Mf-B plus IFN gamma was dependent on L-arginine in the culture, suggesting that arginine metabolites are involved in M theta cytotoxicity. Mf-B induced a small amount of tumor necrosis factor in M theta, and this induction was markedly enhanced by IFN gamma.
Insights
Mycoplasmas activate macrophages to kill tumors, even after treatment. A mycoplasma factor (Mf-B), distinct from lipopolysaccharides, enhances this tumoricidal activity with interferon gamma (IFN gamma).
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Mycoplasmas are known to interact with host immune cells.
- Interferon gamma (IFN gamma) is a key cytokine in immune responses.
- Macrophages (M theta) play a crucial role in tumor surveillance and elimination.
Purpose of the Study:
- To investigate the potential of mycoplasmas and their components to activate macrophages for tumoricidal activity.
- To characterize the nature of the macrophage-activating factor from mycoplasmas.
- To elucidate the mechanism of mycoplasma-induced macrophage activation.
Main Methods:
- Treatment of mycoplasmas and extraction of macrophage-activating factor (Mf-B).
- Co-incubation of macrophages with Mf-B and IFN gamma.
- Assessment of macrophage tumoricidal activity and cytokine production.
- Comparison of Mf-B activity in different mouse strains to differentiate from lipopolysaccharide effects.
Main Results:
- Mycoplasmas, along with IFN gamma, effectively activated macrophages to become tumoricidal.
- The macrophage-activating capacity of mycoplasmas was resistant to heat, acid, alkali, and trypsin treatment.
- Mf-B, extracted from mycoplasmas, activated macrophages in the presence of IFN gamma, with activity independent of lipopolysaccharide response pathways.
- Macrophage cytotoxicity was dependent on L-arginine, and Mf-B induced tumor necrosis factor, enhanced by IFN gamma.
Conclusions:
- Mycoplasmas possess a heat-stable factor (Mf-B) that activates macrophages for tumoricidal functions, distinct from lipopolysaccharides.
- The mechanism involves L-arginine metabolism and induction of tumor necrosis factor, modulated by IFN gamma.
- This finding suggests a potential therapeutic strategy for cancer immunotherapy using mycoplasma-derived factors.