Skin reactions to interferon inoculations are reduced but not abolished by purification.

The skin reactions to partially-purified fibroblast-derived (HulFN-beta) and leucocyte-derived (HulFN-alpha) interferons and to HulFN-alpha of increasing purity were studied in normal volunteers. Reactions consisted of an immediate flare followed by a dense well-circumscribed erythema maximal at 4-8 hours. HulFN-beta caused significantly larger reactions than HulFN-alpha of approximately the same purity. Immediate flare reactions occurred even to the most pure preparation tested but the late reactions were significantly reduced. Experiments suggested that the early reactions to impure HulFN-alpha were in part mediated by local histamine release and late reactions in part by local prostaglandin synthesis. This suggests that interferon itself may not be the cause of general symptoms during a virus illness.