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Human platelets exhibit chemotaxis using functional N-formyl peptide receptors
Meggan Czapiga1, Ji-Liang Gao, Allan Kirk
1Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA.
Experimental Hematology
|January 22, 2005
Summary
Platelets possess functional formyl peptide receptors (FPR) that enable them to perform chemotaxis in response to bacterial N-formyl peptides. This discovery reveals a novel role for platelets in host defense mechanisms.
Area of Science:
- Immunology
- Cell Biology
- Hematology
Background:
- Activated platelets are involved in inflammatory and microbicidal processes.
- Platelets exhibit upregulated surface selectins, shed CD40 ligand, and release microbicidal proteins and microparticles.
Purpose of the Study:
- To investigate if platelets express functional N-formyl peptide receptors (FPR).
- To determine if platelets exhibit chemotaxis in response to bacterial N-formyl peptides.
Main Methods:
- RT-PCR of the MEG-01 cell line, immunoblotting, and calcium mobilization assays to verify FPR expression and function.
- Video microscopy and transwell migration assays to demonstrate platelet chemotaxis.
- Use of FPR-specific antibodies and pertussis toxin to block chemotaxis.
Main Results:
- Specific binding of N-formyl peptides to activated platelets was observed.
- Platelets express functional FPR, demonstrated by calcium mobilization and chemotaxis towards N-formyl peptides.
- Endogenous formyl peptides from necrotic cells induce platelet chemotaxis, but not from apoptotic cells.
Conclusions:
- Platelets express functional formyl peptide receptors, mediating gradient-driven chemotaxis.
- This study establishes a novel role for platelets in host defense.
- Platelet function in microbicidal and other host defense activities warrants reexamination.