Cytokines: the good, the bad, and the unknown.

tiight decades ago, a leading authority on uveitis hypothesized that many patients with uveitis suffered from a disease induced by bacterial toxins. Paradoxically, bacterial toxin in the form of endotoxin evolved as a conventional therapy for uveitis."" Now the conundrum has come full circle; currently, a subcutaneous or intraperitoneal injection of endotoxin serves as a standard model to induce uveitis in laboratory animals."' Cytokines are presumed to be the major mediators of endotoxin-induced inflammation. The simultaneous inflammatory and antiinflammatory ocular effects of endotoxin illustrate the complexity of the actions of cytokines.