The function of IFNLR1 (interferon lambda receptor 1, Ensembl gene identifier ENSG00000185436) is as follows. The IFNLR1/IL10RB dimer is a receptor for the cytokine ligands IFNL2 and IFNL3 and mediates their antiviral activity. The ligand/receptor complex stimulate the activation of the JAK/STAT signaling pathway leading to the expression of IFN-stimulated genes (ISG), which contribute to the antiviral state. Determines the cell type specificity of the lambda interferon action. Shows a more restricted pattern of expression in the epithelial tissues thereby limiting responses to lambda interferons primarily to epithelial cells of the respiratory, gastrointestinal, and reproductive tracts. 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. {ECO:0000269|PubMed:12469119, ECO:0000269|PubMed:12483210, ECO:0000269|PubMed:12521379}.