EOSINOPHIL SURFACE-ANTIGEN EXPRESSION AND CYTOKINE PRODUCTION VARY INDIFFERENT OCULAR ALLERGIC DISEASES

Background: The pathophysiology of chronic ocular allergic disease is not well understood, An eosinophil infiltrate is characteristic of suc h disease and eosinophil activity can be related to disease severity a nd to keratopathy, the most serious complication. Recently, eosinophil s have been shown capable of cytokine production, particularly in alle rgic disease, although the disease-specific cytokine spectrum of tissu e eosinophils is unknown. Objectives: We sought to determine eosinophi l numbers (absolute numbers and percentage of total leukocytes), cell surface antigen expression, and cytokine production in conjunctiva in chronic allergic eye disease and their relationship to corneal involve ment. Methods: Ultrathin sections of conjunctiva were examined by tiss ue staining and by 1- and 2-color immunohistochemistry. Results: Eosin ophil numbers were greater in giant papillary conjunctivitis (GPC) and vernal keratoconjunctivitis (VKC) and not related to corneal involvem ent, The eosinophil expression of the cell surface antigens intercellu lar adhesion molecule-1, CD4, IL-2R, and HLA-DR was greater in atopic keratoconjunctivitis (AKC) and VKC, the disorders with corneal disease , than in GPC, in which the cornea is not involved. For most cytokines , localization to eosinophils was greater for VKC and AKC than for GPC , RANTES, TGF-beta, and TNF-alpha localized to eosinophils in all diso rders. Variations in the pattern of eosinophil-cytokine localization w ere found. In VKC IL-3, IL-5, IL-6, and GM-CSF were prominent; in GPC IL-5 was prominent; and in AKC IL-4, IL-8, and GM-CSF were prominent. Conclusions: Chronic ocular allergic disorders affecting the cornea ar e distinguished from disorders that do not do so by greater expression of eosinophil surface antigens (which may imply greater cell activati on) and differences in cytokine localization to eosinophils, These dif ferences may be secondary to the variations in T-cell subsets or a pri mary phenomenon, Changes in eosinophil function, rather than cell numb ers, may be important in clinical variations, such as keratopathy, and may allow future therapeutic exploitation.