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Hypoferremia in mice and its application to the bioassay of endotoxin
Abstract:
Baker, Phillip J. (University of Wisconsin, Madison), and J. B. Wilson. Hypoferremia in mice and its application to the bioassay of endotoxin. J. Bacteriol. 90:903-910. 1965.-The ability of endotoxin to induce hypoferremia in mice was used for the bioassay of endotoxin. A marked depression in the serum-iron levels of mice occurred 12 hr after the intraperitoneal injection of 0.01 to 100 mug of Escherichia coli endotoxin; similar results were obtained with 1.0 to 100 mug of Brucella abortus endotoxin. This biological response to endotoxin appeared to be specific, reproducible, and dose-dependent. As heat-killed cells of B. abortus and E. coli were also able to induce hypoferremia, this bioassay could be employed for the determination of the endotoxin content of killed-cell preparations. Treatment of endotoxin by acid hydrolysis, acetylation, or pyridine-formic acid greatly diminished the hypoferremic response as well as its lethality for mice. Pretreatment of mice with Thorotrast had little effect upon the ability of endotoxin to induce hypoferremia; however, a stimulation of the activity of the reticuloendothelial system (RES) by treatment of mice with triolein markedly reduced the ability of endotoxin to induce hypoferremia. The relationship between the hypoferremic response to endotoxin and alterations in the activity of the RES are discussed.
Insights
Endotoxin induces hypoferremia (low serum iron) in mice, a response useful for bioassay. This effect is specific, reproducible, and dose-dependent, allowing quantification of endotoxin in bacterial preparations.
Area of Science:
- Microbiology
- Immunology
- Toxicology
Background:
- Bacterial endotoxins are potent immune stimulants.
- Endotoxin's effects on host physiology are complex and not fully understood.
- Accurate bioassays for endotoxin are crucial for research and diagnostics.
Purpose of the Study:
- To investigate the potential of endotoxin-induced hypoferremia in mice as a bioassay for endotoxin.
- To characterize the specificity, reproducibility, and dose-dependency of this response.
- To explore the influence of the reticuloendothelial system (RES) on endotoxin-induced hypoferremia.
Main Methods:
- Mice were injected with varying doses of Escherichia coli and Brucella abortus endotoxins.
- Serum iron levels were measured 12 hours post-injection.
- Endotoxin preparations were chemically modified (acid hydrolysis, acetylation) and tested.
- Mice were pretreated with Thorotrast or triolein to modulate RES activity.
Main Results:
- A dose-dependent decrease in serum iron (hypoferremia) was observed following endotoxin administration.
- The hypoferremic response was specific to endotoxin and reproducible.
- Heat-killed bacteria also induced hypoferremia, enabling endotoxin quantification in cell preparations.
- Chemical modifications of endotoxin reduced its hypoferremic activity and lethality.
- RES stimulation with triolein significantly reduced the hypoferremic response to endotoxin.
Conclusions:
- Endotoxin-induced hypoferremia in mice is a viable and sensitive bioassay for endotoxin.
- The bioassay can be applied to quantify endotoxin in killed-cell bacterial preparations.
- The reticuloendothelial system plays a significant role in modulating the hypoferremic response to endotoxin.