High affinity IgE receptor (Fc epsilon RI) expression on eosinophils infiltrating the lesions and mite patch tested sites in atopic dermatitis.

Expression of the high affinity IgE receptor (Fc epsilon RI) on eosinophils has recently been reported. This led us to evaluate Fc epsilon RI expression on eosinophils in atopic dermatitis (AD). Double immunofluorescence stainings with an anti-Fc epsilon RI monoclonal antibody (mAb) and a polyclonal antieosinophil cationic protein (ECP) antibody were performed on lesional biopsy specimens from patients with AD and from patients with bullous pemphigoid (BP) as controls. In AD and BP lesions, 77% and 70% of eosinophils expressed Fc epsilon RI, respectively. However, the intensity of Fc epsilon RI staining in AD was much stronger than in BP, suggesting upregulation of Fc epsilon RI expression on eosinophils in AD. In addition, the eosinophils infiltrating AD lesions were stained strongly with anti-CD23 mAb and anti-IgE antibody. At the sites of mite patch testing in AD, Fc epsilon RI-, CD23- and IgE-positive eosinophils were observed to the same degree as in the lesions, and a considerable number of mite antigen-bearing eosinophils were detected. Fc epsilon RI and CD23 were both upregulated on the skin-infiltrating eosinophils in AD and bound IgE molecules.