# Dendritic Cell-Derived Extracellular Vesicles Mediate Inflammation in Egg Allergy Patients

## TL;DR

This study explores how dendritic cell-derived extracellular vesicles may contribute to allergic responses in egg allergy patients by influencing T cell behavior.

## Contribution

The study reveals that EVs from activated dendritic cells can shift T cell polarization toward a Th2 profile in egg-allergic individuals.

## Key findings

- EVs from LPS or LPS + OVA-stimulated dendritic cells increased IL-4 and decreased IFN-γ in T cells from egg-allergic donors.
- EVs from LPS-stimulated dendritic cells also suppressed IFN-γ in healthy donors.
- EVs alone could not activate T cells without CD3/CD28 co-stimulation, suggesting they act as a 'third signal' in T cell polarization.

## Abstract

Atopic allergy is rising globally and placing a significant strain on healthcare systems, yet the understanding of the underpinning mechanisms of allergic sensitization remains incomplete. Extracellular vesicles (EVs) have recently emerged as important mediators of immune modulation, due to their diverse cargo, and therefore may play a mechanistic role in allergic sensitization development. Thus, this study investigated whether EVs released by activated dendritic cells (DCs) contribute to allergic sensitization of the common egg allergen, ovalbumin (OVA). DCs were generated from human monocytes cultured with GM-CSF and IL-4, then stimulated with LPS and/or OVA. EVs were subsequently isolated using size-exclusion chromatography and added to freshly isolated naive T cells at defined time points. T cell responses were then analyzed using spectral flow cytometry. The results highlight that EVs derived from LPS or LPS + OVA-stimulated DCs enhanced IL-4 production and reduced IFN-γ production in naive T cells from egg-allergic donors, indicating a shift toward a Th2 profile. In healthy donors, LPS-induced DC EVs also suppressed IFN-γ expression. Notably, EVs alone were insufficient to activate T cells without CD3/CD28 co-stimulation, suggesting that EVs may function as a “third signal” shaping T cell polarization. These findings highlight a potential role for DC-derived EVs in initiating allergic sensitization.