Interferon: Friend or Foe?

INTERFERONS ARE a group of naturally occurring proteins with large molecular weight that have multiple complex activity against viruses, tumors, and even angiogenesis. Of the several types of interferons, interferon alfa has been used most widely for treatment of hairy cell leukemia and other cancers.1Common systemic side effects are a flulike syndrome as well as hypotension and tachycardia.2At high doses, the interferons are neurotoxic, causing electroencephalographic abnormalities similar to those associated with diffuse encephalitis as well as cognitive and behavioral changes.3 Ocular side effects, such as oculomotor paralysis (one case), eyelash hypertrichosis (two cases), and a mostly reversible type of vaso-occlusive retinopathy, have been described.4The retinopathy is characterized by the presence of cotton wool spots, areas of retinal capillary non-perfusion, vascular occlusions, leakage, hemorrhages, and edema of the retina. See also page 1041 The incidence of retinopathy has been recently studied in 63