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Modulation of lipopolysaccharide binding to human granulocytes
A J Weersink1, K P Van Kessel, M E Van der Tol
1Eijkman-Winkler Institute for Medical and Clinical Microbiology, University of Utrecht, The Netherlands.
Immunology
|December 1, 1994
Summary
Human white blood cells (PMN) recognize lipopolysaccharide (LPS) using membrane proteins distinct from CD14. Intracellular granules also contribute LPS-binding proteins to the cell surface for activation.
Area of Science:
- Immunology
- Cell Biology
Background:
- Lipopolysaccharide (LPS) is a key component of Gram-negative bacteria, triggering immune responses.
- Human polymorphonuclear granulocytes (PMN) are crucial in innate immunity, responding to bacterial components like LPS.
Purpose of the Study:
- To investigate the role of membrane proteins in LPS recognition by human PMN.
- To elucidate the mechanism of LPS binding and activation of PMN in the absence of serum.
Main Methods:
- Flow cytometry using fluorescein-labeled LPS (FITC-ReLPS).
- Enzymatic treatments (trypsin, pronase E, proteinase K, neuraminidase) of PMN.
- Luminol-enhanced chemiluminescence to measure PMN response.
- Use of anti-CD14 monoclonal antibody (mAb) 3C10.
- Analysis of PMN from a patient lacking CD14.
Main Results:
- Protease treatment of PMN reduced FITC-ReLPS binding and activation, indicating protein involvement.
- Neuraminidase treatment enhanced FITC-ReLPS binding and activation.
- FITC-ReLPS binding was not inhibited by anti-CD14 mAb 3C10 and occurred in CD14-deficient PMN.
- PMN stimulation with TNF or LPS enhanced FITC-ReLPS binding, dependent on intracellular granules.
Conclusions:
- LPS recognition and activation of human PMN involve cell surface protein structures distinct from CD14.
- Intracellular granules store LPS-binding proteins that translocate to the cell surface upon stimulation, enhancing LPS binding.