Porcine Leukocyte Interferon and Antiviral Activity in Human Cells

Interferon derived from a lower animal source, porcine leukocytes, is shown to have high biological activity in human cell cultures. This interferon shares some biochemical properties with human leukocyte interferon which had been shown previously to protect cells of animal origin. For example, when chromatographed on Phenyl-Sepharose CL-4B, both porcine and human leukocyte interferons bound and could be eluted with 50% ethylene glycol. Similarly, both porcine and human leukocyte interferons did not bind under physiological salt and pH conditions to concanavalin A-agarose. In contrast, the interferon produced by a variety of human and lower animal fibroblasts—which display much reduced cross-species activity—interact strongly with this lectin. Presumably, due to altered glycosylation, leukocyte interferons more easily express cross-species activity. It seems that, generally, interferons elaborated by leukocytes are less restrictive in their species specificity than those elaborated by fibroblasts. Our findings suggest a possible structural homology between human leukocyte and porcine leukocyte interferons similar to those well recognized between various polypeptide hormones of animal and human origin.