Ocular inflammatory effects of intravitreal interleukin 1

Locally injected endotoxin induces potent inflammatory changes in the rabbit eye. To clarify the possible role of interleukin 1 (Il-1), an endotoxin-induced monokine, in rabbit eye inflammation, we injected rabbits with recombinant Il-1 (rIl-1). Twelve and a half to 200 U of intravitreally injected rIl-1 consistently induced inflammation, which was documented using slit-lamp biomicroscopy, histologic methods, or direct quantitation of protein in the aqueous humor. Responses including a cellular infiltrate in the anterior chamber, protein extravasation, and iris vessel dilatation became evident within six hours, peaked at 24 hours, and began to recede by 48 to 72 hours after the injection. Pathologic changes primarily occurred in the anterior chamber and included edema, hemorrhage, and cellular infiltration. Locally injected corticosteroid reduced but did not prevent rIl-1-induced changes in vascular permeability. Heat-inactivated rIl-1 induced minimal changes, as determined by histologic methods, slit-lamp examination, or direct protein measurement. These data support the conclusion that Il-1 should be considered as a potential mediator of ocular inflammation.