SECRETION OF PROINFLAMMATORY CYTOKINES BY HUMAN CONJUNCTIVAL EPITHELIAL-CELLS

The production of cytokines by human conjunctival epithelial cells fol lowing stimulation was investigated. Primary cultures of human conjunc tival epithelial cells were characterized by morphology and keratin ex pression. Cultured epithelial cells were treated with varying concentr ations of lipopolysaccharide, interleukin (IL)-1 beta, calcium ionopho re A(23187), or phorbol myristate acetate, and cytokine secretion was determined over specified intervals, Culture supernatants and cell lys ates were analyzed by ELISA for IL-1 beta, IL-3, IL-4, IL-5, IL-6, IL- 8, IL-11, IL-1 receptor antagonist (IL-1ra), tumor necrosis factor-alp ha (TNF-alpha), and granulocyte-macrophage colony stimulating factor ( GM-CSF). With the exception of LL-1ra, unstimulated conjunctival epith elial cells produced cytokines at relatively low or undetectable level s, IL-1ra was detected in both culture supernatants and cell lysates u nder basal conditions. In response to stimuli, conjunctival epithelial cells secreted the proinflammatory cytokines TNF-alpha, IL-6, IL-8, a nd GM-CSF in a dose- and time-dependent fashion. After stimulation, th e intracellular levels of IL-Ira increased in these cells but the supe rnatant-associated levels remained unchanged. None of the other cytoki nes evaluated (IL-1 beta, IL-3, IL-4, IL-5, and IL-11) were detected i n supernatants or lysates of resting or stimulated cells. These findin gs suggest that conjunctival epithelial cells may contribute to the pa thogenesis of human ocular diseases by production of proinflammatory c ytokines, Further evaluation of these cells as targets of therapy is w arranted.