Delivery of biologically active components of heterologous species interferon isolates

Interferon glycoprotein isolates of heterologous species origin are subjected to treatment in a digestive environment and non-species-specific biologically active fractions thereof are administered, preferably through digestive tract tissue, to the circulatory system of mammals, including humans, to secure antiviral, antiproliferative (e.g., antineoplastic) and immunomodulatory (e.g., immunopotentiating) effects ordinarily associated only with parenteral administration of homologous species interferon.