Interleukin 1 in experimental proliferative vitreoretinopathy

Since proliferative vitreoretinopathy (PVR) is associated with an inflammatory reaction and interleukin-1 (IL-1) initiates a cascade of inflammatory mediators, we determined the intravitreal levels of IL-1 in experimental PVR. In the blood-trauma model of PVR in rabbits, we measured the intravitreal levels of IL-1 alpha and IL-1 beta using a radioimmunoassay and performed immunohistochemical staining of cells from the vitreous. We found that on day 1 polymorphonuclear and from day 2 on mononuclear inflammatory cells predominated in the vitreous. IL-1 alpha- and IL-1 beta-positive cells with a large cytoplasm were observed on days 4 and 8. However, the IL-1 alpha and IL-1 beta concentrations in the vitreous did not exceed the radioimmunoassay sensitivity limit 8 h, 1, 2, 4 and 8 days after trauma, while in 2 control rabbits injected with additional endotoxins we found 5.6 and 8 ng/ml IL-1 beta. We conclude that despite IL-1-positive cells, presumably macrophages, PVR is not associated with high levels of IL-1. No conclusions concerning the low levels of IL-1 alpha and IL-beta can be drawn due to the performance of the RIA.