Abstract: Occurrence of IgE molecules qn Langerhans cells (LC) in lesional sites of atopic dermantis (AD) is a feature of this disease. The events of IgL binding on LC is unknown. In order to address this issue, we examined the presence of the low affinity IgL-Fc receptor (FcεRⅡ/CD23). In 18/26 cases, we detected cells which reacted with one particular antiCD23 mAb MHM6 in Iesional skin. Double immunoiabelling experiments revealed that a portion of MHM6+ cells was CD_1a+LC. Preexposurce of AD sections to glycine-HCl (pH2.5) led to a Loss of MHM6-and anti-IgE-reactive cellular sites. In contrast, the IgE-binding capacity of LC was not affected by acid Ereatment. These observations suggest that FcεRⅡ/CD23, although detected nn LC in AD skin, is nut required for cellular IgE-binding and lead to the hypoEhesis that IgE can bind to LC via a receptor other than FcεRⅡ.

Key words: Atopic dermatitis, Langerhans cell, IgE receptor CD23