Biological properties of human leukocyte interferon components

Human leukocyte interferon, purified approximately 1000-fold by affinity chromatography on immobilized anti-interferon globulins and SDS-Sephadex filtration, was resolved into one major and one minor component by adsorption chromatography on hydroxylapatite and electrophoresis in polyacrylamide gels. These components were indistinguishable in their capacity to protect bovine, porcine and murine cells, and the antiviral activities of both were equally susceptible to reduction by beta-mercaptoethanol. They were neutralized to the same degree of rabbit anti-leukocyte interferon but were not neutralized by rabbit antifibroblast interferon serum. Mice immunized with either component developed antibodies to both but failed to form antibodies against human fibroblast interferon. Our present evidence indicates that the two components posses at most only minor structural and antigenic dissimilarities.