Role of eosinophil-chemotactic C-C chemokines in cutaneous inflammation

In the dermal sites of atopic skin, eosinophil (Eo) granule protein or more rarely intact Eos represent a characteristic histological feature. We addressed the question of whether lesional scales of patients with various eosinophilic skin disorders contain Eo attractant and tried to characterize it biochemically. In scales of a patient with drug reaction, heparin-binding Eo attractants could be identified. High-performance liquid chromatographic analyses together with specific ELISA and Western blot analyses revealed identity with RANTES. No other heparin-binding Eo chemotaxin could be identified. HPLC analysis of pooled lesional scale extracts of patients with atopic dermatitis showed fractions containing only weak heparin-binding Eo-chemotactic activity, which, however, showed RANTES immunoreactivity. In experiments to elucidate the putative cellular origin of Eo-attracting chemokines in human skin we investigated supernatants of atopic skin we investigated supernatants of atopic skin-derived T lymphocytes as well as supernatants of stimulated dermal fibroblasts for Eo-chemotactic factors. Unexpectedly, we did not find any heparin-bound Eo attractants in supernatants of stimulated cultured atopic skin-derived T lymphocyte clones, whereas fibroblasts produced RANTES as well as granulocyte-macrophage colony-stimulating factor. Therefore, fibroblasts are likely source of eosinophil attractant cells, which could contribute to the Eo infiltrate. Selectivity of the infiltrate might come from selective induction of RANTES and/or induction of other as yet unidentified Eo-specific chemokines.