Characterization of dendritic cell phenotype in allergic conjunctiva: Increased expression of Fc&RI, the high-affinity receptor for immunoglobulin e

Abstract

Purpose: Dendritic cells (DCs) express the high-affinity receptor for IgE (FcRI) on their surface, which may enhance their ability to capture and internalize antigens for presentation to T-lymphocytes. The aim of this study was to determine if expression of FcRI DCs is increased in the conjunctivae of vernal keratoconjunctivitis (VKC) patients compared with those of normal controls.Methods: Conjunctival biopsies were obtained from non-atopic and VKC patients. Double immunohistochemical staining was carried out using antibodies against FcRI and the CD1a antigen, a DC marker. The double-positive cells were counted in five representative fields of view for each conjunctival sample.Results: Fc&RI+ CD1a+ cells were present in significantly higher numbers in VKC conjunctivae compared with normal controls (mean cell count of 21.3 in VKC vs5.0 in controls, P<0.005). In normal patients the Fc&RI-expressing DCs tended to be confined to the epithelial layer or the superficial substantia propria, but in the VKC samples these FcRI cells were mainly concentrated in the deeper substantia propria.Conclusions: Fc&RI+ DC numbers are elevated in the conjunctivae of VKC patients, a finding consistent with the results of other studies focusing on atopic conditions. Elevated expression of Fc&RI on DCs would facilitate antigen presentation and enhance T-cell priming, thereby contributing to ocular symptoms. © 2009 Macmillan Publishers Limited. All rights reserved.