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Characterization of soluble CD40 ligand released from human activated platelets
1Division of Human Ontogeny and Childhood Development, Graduate School, Tokyo Medical and Dental University, Japan.
Journal of Medical and Dental Sciences
|August 6, 2002
Summary
Human platelets release soluble CD40 ligand (sCD40L) upon activation, contributing to inflammation and immune responses. This release, mediated by metalloproteinases, is absent in X-linked hyper IgM syndrome patients.
Area of Science:
- Immunology
- Hematology
- Cell Biology
Background:
- CD40 ligand (CD40L) is crucial for immune responses and inflammation.
- Platelets are known to play roles beyond hemostasis.
Purpose of the Study:
- To investigate the release of soluble CD40 ligand (sCD40L) from activated human platelets.
- To determine the mechanism and functional implications of sCD40L release from platelets.
Main Methods:
- Human platelets were activated in vitro using collagen or thrombin.
- Soluble CD40 ligand (sCD40L) levels in culture supernatants were measured over time.
- The effect of metalloproteinase inhibitor KB8301 on sCD40L release was assessed.
- sCD40L levels were examined in platelets from patients with X-linked hyper IgM syndrome (XHIM).
Main Results:
- Soluble CD40 ligand (sCD40L) was detected in platelet supernatants within 30 minutes of activation, peaking at 3 hours.
- sCD40L release was inhibited by the metalloproteinase inhibitor KB8301, suggesting cleavage of membrane-bound CD40L.
- sCD40L was undetectable in activated platelets from XHIM patients.
- sCD40L demonstrated biological activity on vascular endothelial cells and B cells.
Conclusions:
- Human platelets release biologically active soluble CD40 ligand (sCD40L) upon activation.
- Platelet-derived sCD40L is generated through metalloproteinase-dependent cleavage of membrane-bound CD40L.
- Platelets contribute to inflammatory and humoral immune responses through the release of sCD40L.
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