Chronologic analysis of eosinophil granule protein deposition and cell adhesion molecule expression in mite...

To investigate the process of eosinophil recruitment in atopic dermatitis (AD), patch testing with crude dust-mite allergens was performed on normal-appearing skin of 9 adult AD patients with high levels of mite-specific IgE antibodies. Positive reactions were observed in 6 AD subjects, whereas 0 of 7 control subjects showed positive reactions to mite allergens. Positive reaction sites were biopsied chronologically and studied histologically and immunohistochemically. Eosinophils were seen in postcapillary venules in the dermis at 2 h, followed by infiltration of eosinophils at 6 h which peaked at 24 and 48 h. In the epidermis, eosinophilic spongiosis was seen at 48 h. Positive reactions against eosinophil granule proteins were observed in connective tissues as well as on eosinophils. Almost all infiltrating eosinophils were positive for BMK-13 (an antibody against major basic protein); half of them were positive for EG2 (an antibody against eosinophil cationic protein). With regard to adhesion molecules, expression of E-selectin and intercellular adhesion molecule-1 endothelial cells was up-regulated as infiltrating eosinophils increased in number. These findings suggest that eosinophil transmigration from endothelial cells and eosinophil degranulation play important roles in initiating early AD lesions induced by transepidermal mite allergen permeation.