Phenotype and function of IgE-binding monocytes in equine Culicoides hypersensitivity.
Authors: Larson Elisabeth M, Babasyan Susanna, Wagner Bettina
Journal: PloS one
Summary
# Editorial Summary: IgE-binding Monocytes in Equine Culicoides Hypersensitivity Researchers at Cornell University characterised IgE-binding monocytes in horses for the first time, investigating whether these cells promote or dampen allergic responses in Culicoides hypersensitivity (sweet itch). Using flow cytometry, they identified and tracked IgE+ monocytes in both allergic and non-allergic horses with natural midge exposure over a 12-month period, measuring changes in cell phenotype, surface markers, and cytokine production. Notably, the frequency and basic characteristics of IgE-binding monocytes remained stable across all horses regardless of disease status or seasonal Culicoides exposure, though all horses upregulated the CD16 marker following initial exposure. When activated through their IgE receptors, these monocytes produced interleukin-10 (IL-10)—a regulatory, anti-inflammatory cytokine—but notably did *not* produce pro-inflammatory mediators such as IL-4, IL-17A, or IFN-γ, suggesting a protective rather than disease-driving role. The consistent positive correlation between serum total IgE and monocyte IgE surface density across healthy and affected horses points to a shared underlying immunological mechanism. Understanding whether IgE-binding monocytes represent a regulatory checkpoint or a therapeutic target could reshape how practitioners approach managing IgE-mediated allergic diseases in equines.
Read the full abstract on PubMed
Practical Takeaways
- •Understanding IgE-binding monocyte biology may eventually lead to targeted immunological interventions for Culicoides hypersensitivity in horses
- •The consistent presence of these cells in both allergic and nonallergic horses suggests individual variation in immune responsiveness rather than simple presence/absence of disease mediators
- •IL-10 production by these cells indicates a potential regulatory role that may differ between hypersensitive and nonallergic individuals
Key Findings
- •IgE-binding monocytes in equine blood identified as IgE+/MHCIIhigh/CD14low cells that bind IgE through FcεRI variant
- •IgE-binding monocyte phenotype and frequency remained consistent regardless of Culicoides exposure in both allergic and nonallergic horses
- •All horses upregulated CD16 expression on IgE-binding monocytes following initial Culicoides exposure
- •IgE-binding monocytes produce IL-10 but not IL-4, IL-17A, or IFN-γ after IgE crosslinking, suggesting regulatory rather than pro-inflammatory function