Abstract OBJECTIVE: Eotaxin-1 and eotaxin-2 are potent eosinophil chemotactic and activating peptides that may be implicated in the pathogenesis of the chronic allergic eye diseases vernal keratoconjunctivitis (VKC) and atopic keratoconjunctivitis (AKC). The purpose of this study was to measure these chemokines in tear and mucus samples of active-disease patients and in vitro cultured conjunctival epithelial cells and fibroblasts. DESIGN: Comparative, observational case series and in vitro study. PARTICIPANTS: Sixteen patients with clinically active and untreated VKC or AKC, six age-matched control patients, and five nonactive seasonal allergic conjunctivitis patients. METHODS: Tears were collected from the active VKC and AKC patients, and from the normal patients. Mucus was collected from six of these VKC patients. Tears were also collected from an additional five allergic patients after obtaining a positive reaction to conjunctival allergen challenge. Conjunctival epithelial cell and conjunctival fibroblast cultures were exposed to interleukin (IL)-4, IL-13, and tumor necrosis factor-alpha (TNF-alpha), or to combinations of these cytokines. MAIN OUTCOME MEASURES: Levels of eotaxin-1 and eotaxin-2 in tears, mucus, and culture medium. RESULTS: High levels of eotaxin-1 and eotaxin-2 were found in mucus of VKC patients, whereas only eotaxin-2 was found to have increased significantly in tears of VKC and AKC patients compared with those of normal patients. Mucus contained higher levels of chemokines than did tears. Both tear eotaxin-1 and eotaxin-2 were correlated significantly with the percent of eosinophils in tear fluid. Eotaxin-1 also was correlated significantly with the sum clinical score and corneal involvement in VKC patients. Conjunctival epithelial cells in culture did not produce eotaxin-1 or eotaxin-2, either at baseline or after cytokine exposure. Conjunctival fibroblasts produced eotaxin-1 only after exposure to IL-4, TNF-alpha, and the combination of IL-4 plus TNF-alpha or IL-13 plus TNF-alpha. CONCLUSIONS: Eotaxin-1 and eotaxin-2 are implicated in eosinophil recruitment and in the pathogenesis of VKC and AKC. Cytokine-stimulated conjunctival fibroblasts may be one source of eotaxin-1 in severely allergic tissues