Elevated levels of eotaxin and interleukin‐5 in blister fluid of bullous pemphigoid: correlation with tissue eosinophilia

BACKGROUND: Bullous pemphigoid (BP) often provokes blood and tissue eosinophilia, which suggests that some chemoattractants modulate the eosinophil infiltration in BP. Eotaxin, a CC chemokine, strongly attracts eosinophils, and interleukin (IL)-5 induces eosinophil differentiation, proliferation and colony formation in vitro. OBJECTIVES: To examine the correlation between levels of eotaxin and IL-5 and the number of lesional eosinophils, and the expression of eotaxin in BP lesions. PATIENTS/METHODS: In this study we measured eotaxin and IL-5 levels in blister fluid of BP by enzyme-linked immunosorbent assay. We also examined the expression of eotaxin in BP lesions by immunohistochemistry. RESULTS: Both eotaxin and IL-5 were detected at high levels in BP blister fluid. Blister fluid eotaxin, but not IL-5 levels, correlated significantly with the number of dermal infiltrating eosinophils. By immunohistochemistry, eotaxin was strongly expressed in epidermal keratinocytes around BP blisters. CONCLUSIONS: These findings suggest that eotaxin and IL-5 are strongly associated with the tissue eosinophilia of BP. Therapies which aim to inhibit production of eotaxin and IL-5 may improve the inflammation and blister formation in BP.