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Binding and neutralization of endotoxin by Limulus antilipopolysaccharide factor
H S Warren1, M L Glennon, N Wainwright
1Department of Pediatrics, Massachusetts General Hospital, Boston.
Infection and Immunity
|June 1, 1992
Summary
Limulus antilipopolysaccharide factor (LALF) effectively binds and neutralizes lipopolysaccharide (LPS) from gram-negative bacteria. This study confirms LALF
Area of Science:
- Biochemistry
- Immunology
- Microbiology
Background:
- Lipopolysaccharide (LPS) is a major component of the outer membrane of gram-negative bacteria.
- LPS can trigger potent inflammatory responses and septic shock.
- Limulus antilipopolysaccharide factor (LALF) is a horseshoe crab protein with known antimicrobial properties.
Purpose of the Study:
- To investigate the binding affinity of LALF to LPS.
- To evaluate the neutralizing capacity of LALF against LPS-induced biological effects.
Main Methods:
- Purification of LALF and coupling to agarose beads for binding assays.
- Competition assays using radiolabeled LPS and unlabeled LPS.
- Assessment of LPS neutralization through in vitro and in vivo assays (mitogenicity, pyrogenicity, lethality, physiological effects in sheep).
Main Results:
- LALF-coupled beads demonstrated significant binding of LPS from both rough and smooth strains of gram-negative bacteria.
- LALF binding to LPS was dose-dependent.
- LPS pre-incubation with LALF reduced its mitogenic, pyrogenic, and lethal activities, and attenuated LPS-induced fever, neutropenia, and pulmonary hypertension in vivo.
Conclusions:
- LALF exhibits direct binding to LPS.
- LALF effectively neutralizes the biological activities of LPS, suggesting its potential as a therapeutic agent against gram-negative bacterial infections.