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The inhibitory effect of polymyxin B on endotoxin-induced endogenous pyrogen production
Abstract:
The effect of polymyxin B (PMB) on the endogenous pyrogen (EP)-induced property of lipopolysaccharide (LPS) in vitro was examined. PMB inhibited LPS when added to leukocyte suspension 5 min before or up to 30 min after the addition of LPS. The inhibitory effect was dose-related and appeared to be specific for LPS (including naturally occurring endotoxin). EP production in response to a different stimulus (staphylococci) was not prevented even when LPS-PMB complexes were presumably present. These data suggest that when experimental agents are found to stimulate the production of EP or lymphocyte activating factors (LAF, interleukin-1) in vitro, or when apparently spontaneous production of EP or LAF is seen, incubation with PMB may be a useful technique to exclude th effects of endotoxin contamination - especially when negative results have been obtained in the limulus gelation test.
Insights
Polymyxin B (PMB) effectively inhibits lipopolysaccharide (LPS)-induced endogenous pyrogen (EP) production in vitro. This suggests PMB is a valuable tool for excluding endotoxin contamination in experimental settings.
Area of Science:
- Immunology
- Microbiology
- Pharmacology
Background:
- Endogenous pyrogens (EPs) mediate fever and inflammation.
- Lipopolysaccharide (LPS) is a potent stimulator of EP production.
- Endotoxin contamination can confound in vitro immunological studies.
Purpose of the Study:
- To investigate the in vitro effect of polymyxin B (PMB) on LPS-induced EP production.
- To determine if PMB can be used to exclude endotoxin contamination in experimental assays.
Main Methods:
- In vitro incubation of leukocyte suspensions with LPS and PMB.
- Dose-response analysis of PMB's inhibitory effect.
- Testing PMB's specificity against other stimuli like staphylococci.
Main Results:
- PMB significantly inhibited LPS-induced EP production when added before or after LPS.
- The inhibitory effect of PMB was dose-dependent and specific to LPS.
- PMB did not prevent EP production induced by staphylococci.
Conclusions:
- Polymyxin B is an effective inhibitor of LPS-induced EP production in vitro.
- PMB can be utilized as a technique to rule out endotoxin contamination.
- This method is particularly useful when Limulus gelation tests yield negative results.