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Published on: June 20, 2018
Vesicle-mediated secretion of human eosinophil granule-derived major basic protein
Rossana C N Melo1, Lisa A Spencer, Sandra A C Perez
1Laboratory of Cellular Biology, Department of Biology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil.
Summary
Major basic protein (MBP) can be secreted from human eosinophils via piecemeal degranulation (PMD) using transport vesicles. This finding is crucial for understanding allergic diseases and inflammation involving eosinophils.
Area of Science:
- Cell Biology
- Immunology
- Pathology
Background:
- Major basic protein (MBP) is a key cationic protein in human eosinophil granules.
- MBP secretion contributes to the immunopathogenesis of various diseases.
- Piecemeal degranulation (PMD) is a proposed mechanism for eosinophil granule protein release via vesicles.
Purpose of the Study:
- To investigate the secretion of eosinophil granule-derived MBP through PMD.
- To evaluate the role of vesicular trafficking in MBP release from human eosinophils.
Main Methods:
- Immunofluorescence and pre-embedding immunonanogold electron microscopy (EM) were used to study MBP localization in human eosinophils.
- Eotaxin stimulation was employed to assess MBP secretion.
- Transport vesicle quantification was performed in eosinophils from patients with hypereosinophilic syndrome (HES).
Main Results:
- Vesicular trafficking of MBP was observed in eotaxin-stimulated eosinophils.
- MBP was found within eosinophil sombrero vesicles (EoSVs) and other secretory compartments.
- HES eosinophils showed increased numbers of MBP-containing secretory compartments.
- Unstimulated eosinophils also contained MBP in secretory vesicles, co-localizing with CD63.
Conclusions:
- Eosinophil MBP can be mobilized from granules via PMD into secretory vesicles.
- Both granule-stored and vesicle-stored MBP pools are available for secretion.
- Understanding PMD's role in MBP release is vital for allergic and inflammatory diseases.
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