House dust mite (HDM) antigen in naturally occurring lesions of atopic dermatitis (AD): the relationship between HDM antigen in the skin and HDM antigen-specific IgE antibody.

To elucidate the etiological role of house dust mite (HDM) antigen in the pathogenesis of atopic dermatitis (AD), we conducted immunohistochemical studies on the localization of HDM antigen in naturally occurring lesions of AD. HDM antigens were found in the epidermis and dermis in 19 of 38 cases. All of the 19 patients had HDM antigen-specific IgE antibody, but HDM antigen was not detected in the lesions of patients without HDM antigen-specific IgE or in control skin specimens. Most HDM antigens were located on Langerhans cells (LCs) or near helper T cells. Our findings suggest that HDM antigen is the causative factor in the development of eczematous lesions of AD, and thus we hypothesized that IgE-mediated allergic contact sensitivity to HDM antigen plays an important role in the pathogenesis of AD.