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Lipopolysaccharide induces up-regulation of CD14 molecule on monocytes in human whole blood
A Marchant1, J Duchow, J P Delville
1Department of Immunology, Hôpital Erasme, Université Libre de Bruxelles, Belgium.
Abstract:
We examined by flow cytometry the expression of lipopolysaccharide (LPS) receptor CD14 molecule on monocytes after addition of LPS to human whole blood. Within 30 min LPS induced an increase in monocyte CD14 expression, peaking between 1 and 3 h and followed by a slow decrease. Maximal increase in anti-CD14 monoclonal antibody binding sites was estimated as twofold the basal value. This effect, already observed with very low concentrations of LPS (10 pg/ml), was dose dependent. Protein synthesis was not involved in the CD14 hyperexpression since it was not influenced by co-incubation with cycloheximide. Finally, LPS-induced up-regulation of monocyte CD14 was associated with an increased binding of fluoresceinated LPS. We conclude that LPS in whole blood up-regulates the expression of its own CD14 receptor on monocytes, a phenomenon that could be relevant to the pathogenesis of gram-negative sepsis.
Insights
Lipopolysaccharide (LPS) rapidly increases its own receptor, CD14, on monocytes in human blood. This LPS-induced CD14 upregulation may play a role in gram-negative sepsis pathogenesis.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Lipopolysaccharide (LPS) is a key component of gram-negative bacteria.
- CD14 is a well-established receptor for LPS on myeloid cells.
Purpose of the Study:
- To investigate the effect of LPS on CD14 expression in human whole blood.
- To determine the kinetics and characteristics of LPS-induced CD14 upregulation on monocytes.
Main Methods:
- Flow cytometry was used to analyze CD14 expression on monocytes.
- Human whole blood was incubated with varying concentrations of LPS.
Main Results:
- LPS induced a rapid, dose-dependent increase in monocyte CD14 expression within 30 minutes, peaking at 1-3 hours.
- The upregulation of CD14 was not dependent on new protein synthesis.
- Increased CD14 expression correlated with enhanced binding of fluoresceinated LPS.
Conclusions:
- LPS upregulates its own receptor, CD14, on monocytes in whole blood.
- This phenomenon may be significant in the pathogenesis of gram-negative sepsis.