Comparison of uveitis induced by interleukin-8 (IL-8) and endotoxin in rabbits

IL-8 is a potent chemoattractant which has been postulated to play a role in the cytokine cascade associated with uveitis. The authors studied the effect of intravitreal IL-8 on the induction of uveitis in the rabbit. IL-8 at varying concentrations (1 ng, 10 ng or 100 ng) or endotoxin (100 ng) was injected intravitreally within the rabbit eye. At 6, 24 and 48 hours following injection the induction of uveitis was evaluated by clinical scoring, anterior chamber (AC) leukocyte count, AC protein concentration and histopathology in 15 rabbits. Only the 100 ng concentration of IL-8 induced uveitis at 6 and 24 hours by clinical scoring and AC leukocyte count; the AC protein concentration remained normal. In contrast, endotoxin caused a severe uveitis with a significant increase in all the parameters evaluated. The authors conclude that intravitreal IL-8, in the concentrations studied, induces a limited uveitis which is detectable at six hours and resolves within 48 hours. It is characterized by leukocyte infiltration without an increased AC protein concentration. Thus, IL-8 may play a role in the cytokine cascade involved in the induction of uveitis.