Antiproliferative and antiviral activities of human leukocyte interferons

Abstract The antiproliferative effects of purified human leukocyte interferons were measured by their ability to inhibit cell multiplication of the human lymphoblastoid Daudi cell line. The growth-inhibitory and antiviral activities fractionate together throughout the purification of leukocyte interferon. In all cases, those fractions which exhibited antiviral activity also inhibited proliferation of Daudi cells. The final stage of protein purification, high-performance liquid chromatography on octyl-silica particles (pH 4.0), separated at least eight species of leukocyte interferon, all of which possessed growth-inhibitory activity. Because these two biological activities purify together and because the homogeneous species exhibit both activities, we conclude that the antiproliferative and the antiviral activities are both intrinsic properties of these human leukocyte interferons. However, the ratio of the growth-inhibitory to antiviral activity was not constant among the species. In addition, the ratio of the antiviral activity on human cells to that on bovine cells varied from species to species. We conclude that the individual members of the family of human leukocyte interferon proteins differ in structure and that these structural differences manifest themselves as variations in their intrinsic biological activities.