Interferon alfa induces leukocyte capillary trapping in rat retinal microcirculation.

Background: Interferon alfa has been suggested as a possible treatment for choroidal neovascularization. However, retinal complications following interferon therapy have been reported.
Objective: To evaluate the effects of interferon alfa on leukocyte dynamics in the rat retinal microcirculation.
Methods: Interferon alfa of different doses was intravenously administered in rats. Leukocyte dynamics were observed with acridine orange digital fluorography, which uses a nuclear fluorescent dye of acridine orange and scanning laser ophthalmoscopy. This technique allows visualization of leukocyte movements in the retinal microcirculation in vivo.
Results: After interferon alfa was administered, leukocytes adhered to vascular walls and became trapped in the retinal microcirculation. Leukocyte trapping was dose-dependent.
Conclusions: Interferon alfa increased leukocyte adherence to vascular endothelium and subsequent leukocyte trapping in the retinal capillaries. Interferon alfa may activate leukocytes, and activated leukocytes may be involved in the pathogenesis of microinfarction associated with interferon-induced retinopathy.