Cytokine with immunomodulatory activity. Up-regulates MHC class I antigen expression. Displays potent antiviral activity. Also displays antitumor activity. Ligand for the heterodimeric class II cytokine receptor composed of IL10RB and IFNLR1. The ligand/receptor complex seems to signal through the Jak-STAT pathway. Seems not to be essential for early virus-activated host defense in vaginal infection, but plays an important role in Toll-like receptor (TLR)-induced antiviral defense. Plays a significant role in the antiviral immune defense in the intestinal epithelium.