Recombinant interferons increase macrophage Fc receptor capacity

We utilized recombinant interferon preparations to confirm and extend our previous findings that biochemically purified preparations of interferon augment Fc receptor (FcR)-mediated functions. Five different recombinant human α-interferons (IFN) were tested and increased Fc-mediated phagocytosis and binding of opsonized erythrocytes with varying efficiencies. We found, however, that when the different α-IFN species were ranked with respect to their FcR-enhancing activity, their hierarchy differed from those reported for antiviral, antiproliferative, and NK cell-inducing activities. Recombinant murine γ-IFN was also found to increase Fc-mediated phagocytosis, but was significantly more potent than either β-IFN or recombinant α-IFN when compared on the basis of antiviral activity. A comparison of the amino acid sequences of the recombinant IFN may help define functional domains of the molecule.