Antigenic properties and heterospecific antiviral activities of human leukocyte interferon species.

Human interferon obtained in peripheral leukocytes was purified approximately 1000-fold by affinity chromatography on anti-leukocyte interferon globulins coupled to Sepharose 4B, and by filtration on SDS-Sephadex G-100. The interferon was subsequently resolved into two molecular species by adsorption chromatography on SDS-hydroxylapatite. The two species which were eluted at different phosphate molarities from hydroxylapatite, could also be distinguished on the basis of electric charge properties and they migrated at different rates in SDS-polyacrylamide gels. Crossneutralization tests with monospecific rabbit anti-leukocyte and anti-fibroblast interferon sera revealed that the two species possessed leukocyte interferon-specific antigenic determinants. Both were immunogenic in mice and they were neutralized to a comparable degree by antisera against either component. A variable degree of antiviral activity was expressed by both interferon components in bovine, porcine and murine cells. However, the two interferon species were equally active in this respect, and the protective effects exhibited in homologous and heterologous cell cultures were similarly susceptible to reduction by beta-mercapto-ethanol. We conclude that the two molecular species of human leukocyte interferon are biologically similar.