Role Of Fc Gamma Ri In Antigen-Dependent Eosinophil Activation In Patients With Allergic Rhinitis

Background The eosinophil (Eo) activation is a crucial factor evoking allergic rhinitis (AR) attacks; factors; the mechanism of triggering Eo activation remains to be further investigated. The interaction of antigen (Ag) and antibody plays a critical role in evoking allergy attacks. This study aims to elucidate the role of Fc gamma RI, the high affinity receptor of IgG, in the Ag-mediated Eo activation. Methods Nasal lavage fluids (NLF) were collected from AR patients and healthy control (HC) subjects. Eos were isolated by flow cytometry cell sorting and analyzed by pertinent immunological approaches. Results Eos composed more than 60% of the cellular components in AR NLF. Exposure to specific Ags (sAgs) in the culture triggered Eos to release inflammatory mediators. High levels of Fc gamma RI were detected on the surface of AR NLF Eos. Exposure to lipopolysaccharide markedly increased the Fc gamma RI expression in naive Eos, which could be bound by Ag-specific IgG (sIgG) to form complexes on the surface of Eos; this made Eos at the sensitized status. Eos bore with the sIgG/Fc gamma RI complexes could be activated upon exposure to sIgG in the culture; these Eos can be designated as Ag-specific Eos. Passive transfer of Ag-specific Eos resulted in profound AR response in mice upon sAg challenge. Depletion of Fc gamma RI on Eos efficiently abolished AR response in mice. Conclusions AR Eos express high levels Fc gamma RI, that can be bound by sIgG to make Eos sensitized. Re-exposure to specific Ags can activate the sensitized Eos.