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Antigen-presenting cell exosomes are protected from complement-mediated lysis by expression of CD55 and CD59
Aled Clayton1, Claire L Harris, Jacquelyn Court
1Section of Clinical Oncology and Palliative Medicine, Department of Medicine, University of Wales College of Medicine, Velindre Hospital, Whitchurch, Cardiff, GB. aled.Clayton@velindre-tr.wales.nhs.uk
European Journal of Immunology
|March 21, 2003
Summary
Antigen-presenting cell-derived exosomes express complement regulators CD55 and CD59, protecting them from immune attack. This finding is crucial for developing exosomes as effective cell-free immunotherapy tools.
Area of Science:
- Immunology
- Cell Biology
- Nanomedicine
Background:
- Exosomes, secreted nanovesicles from antigen-presenting cells, are investigated for immunotherapy.
- Liposomes can trigger complement activation, causing degradation and toxicity.
- Exosomes may also activate the complement system, limiting their therapeutic potential.
Purpose of the Study:
- To investigate the expression and function of complement regulatory proteins on exosomes.
- To determine if exosomes are protected from complement-mediated lysis.
Main Methods:
- Examined expression of CD46, CD55, and CD59 on exosomes.
- Used antibody blocking of CD55 and CD59 in human serum.
- Assessed C3b deposition and exosome lysis.
Main Results:
- Exosomes express GPI-anchored CD55 and CD59, but not CD46.
- Blocking CD55 or CD59 increased complement-mediated exosome lysis.
- Simultaneous blockade of CD55 and CD59 led to further increased lysis.
Conclusions:
- Exosomes utilize GPI-anchored complement regulators (CD55, CD59) for survival.
- These regulators protect exosomes from complement activation in the extracellular environment.
- Understanding this mechanism is key for exosome-based immunotherapy development.