134 Original Article Eotaxin Expression in Patients with Papular Urticaria: An Immunohistochemical Study Maged Elbattawy, M.D.*, Wedad Mostafa, M.D.*, Naglaa Nabil, M.D.*, Soheir Mahfouz, M.D.† and Wafaa Abd El Aziz, M.D.‡ *Department of Dermatology, †Department of Pathology, Cairo University, Faculty of Medicine and ‡Al Haud Al-Marsoud Hospital, Egypt. Background. Papular urticaria is a chronic allergic disease characterized by selective accumulation of eosinophils. Eotaxin is a chemokine that is a potent and selective chemoattractant for eosinophils both in vivo and in vitro. To date, eotaxin has not been studied in papular urticaria. Objective. To detect eotaxin, semiquantitatively, in lesional skin of patients with papular urticaria and to investigate the presence of any correlation between eotaxin density and the various demographic, clinical, and histopathological features of the disease. Patients and methods. The study included 29 patients with papular urticaria and 32 control subjects. Immunohistochemical study of the amount and distribution pattern of eotaxin was performed using eotaxin (C-19) polyclonal antibody (IgG). Results. Eotaxin expression was more signiicantly evident in the patient group than in controls (p < 0.001) and appeared to be positively correlated to the inlammatory cell population. Epidermal eotaxin distribution pattern was absent or patchy in the patient group whereas in healthy controls the predominant pattern was linear and continuous along the basal cell layer. A predominant dermal eotaxin distribution, mostly in interstitial and perivascular compartments, was observed in the patient group. Lesion severity did not correlate statistically with eotaxin expression; neither did the patient age, sex, disease duration, recurrence rate, clinical features or histopathological patterns. Conclusion. Eotaxin expression is deranged in epidermis and upregulated in the dermis of patients with papular urticaria compared with healthy controls. These indings may represent a possible mechanism for promoting tissue inlammation in this disease which needs further research. (J Egypt Women Dermatol Soc 2010; 7: 134 - 140) Keywords. CCL11, eosinophils, eotaxin, immunohistochemistry, papular urticaria Corresponding Author. Naglaa Nabil, M.D., Assistant Professor of Dermatology, Faculty of Medicine, Cairo University, Egypt. E mail. nnradw@yahoo.com Conlict of interest. None declared. Copyright © 2010 Egyptian Women Dermatologic Society. All rights reserved. P apular urticaria is a common and often distressing childhood disorder manifested by chronic or recurrent pruritic papules. Individual papules may be preceded by a wheal and often have a central punctum. They may be excoriated, licheniied or secondarily infected with crust formation. After resolution, it may result in temporary post-inlammatory erythema or pigmentation. Papular urticaria may represent a clinical challenge, particularly during spring and summer 1 . Food and drug allergy or insect reactions are suspected etiological factors. The majority of authors believe the disease to be an epizoonosis, i.e. a disease caused by insect bites or stings, e.g., leas, mites, mosquitoes 2 . It has been considered as an "id- reaction" to bites from insects such as mosquitoes, leas, mites, and bedbugs 3 . The irritation is produced by the injection into the skin of a luid secreted by the salivary glands of the parasite. Some persons have hypersensitivity to the secretion and manifest immediate or delayed reactions at the site of the bite 4 . The histopathologic features include mild acanthosis, mild spongiosis, exocytosis of lymphocytes, mild subepidermal edema, extravasation of erythrocytes, a supericial and deep mixed inlammatory cell iniltrate of moderate density and interstitial eosinophils 5 . The predominance of eosinophils within the granulocytic iniltrate may suggest an important role for these cells in the pathogenesis of papular urticaria 6 . The selective accumulation of eosinophils at sites of allergic inlammation (for example, asthma, rhinitis and atopic dermatitis) suggested the existence of endogenous eosinophil-speciic chemoattractants 7 - 9 . Eotaxin is a chemokine that is a potent and selective chemoattractant for eosinophils in both in vivo and in vitro test systems. The potency and rapid action of eotaxin in inducing selective eosinophil accumulation suggests an integral role for this chemokine in eosinophil traficking 7,10 . This selective eosinophil chemoattractant activity of eotaxin might explain tissue eosinophilia observed in papular urticaria 7 . The objective of the study was to detect eotaxin, semiquantitatively, using an immunostaining