Angiography with fluorescein-labeled dextrans in a primate model of uveitis
S. L. Lightman, L. E. Caspers-Velu, S. Hirose, R. B. Nussenblatt and A. G. Palestine
Sequential fluorescein angiography, using fluorescein-labeled dextran
molecules of several different sizes, was carried out in monkeys with
intraocular inflammation induced with interphotoreceptor retinoid-binding
protein. The vascular leakage seen with the dextrans was compared with that
seen with standard fluorescein sodium angiography. The angiograms
demonstrated that different-sized leaks appear in the retinal vessels in
adjacent areas during the course of the inflammation. Most retinal vessels
leaked only fluorescein sodium and no dextran of any size, suggesting that
it is the unbound fluorescein that leaks out of these vessels and not
fluorescein bound to plasma albumin. It was not possible to tell by
clinical examination which areas would leak the larger-molecular weight
tracers. Ultrastructural studies of the veins leaking the dextrans revealed
areas of abnormal endothelial tight junctions, whereas the tight junctions
were normal in areas where leakage occurred with fluorescein alone.
