© 2018 Harris et al. IFN and IFN are interferons that induce microbial immunity at mucosal surfaces and in the skin. They are members of the type-I interferon (IFN) family, which consists of 16 different IFNs, that all signal through the common IFNAR1/IFNAR2 receptor complex. Although IFN and IFN have unique expression and functional properties, their biophysical properties have not been extensively studied. In this report, we describe the expression, purification, and characterization of recombinant human IFN and IFN. In cellular assays, IFN and IFN exhibit 1000-fold lower potency than IFN2 and IFN. The reduced potency of IFN and IFN are consistent with their weak affinity for the IFNAR2 receptor chain. Despite reduced IFNAR2-binding affinities, IFN and IFN exhibit affinities for the IFNAR1 chain that are similar to other IFN subtypes. As observed for cellular IFNAR2 receptor, the poxvirus antagonist, B18R, also exhibits reduced affinity for IFN and IFN, relative to the other IFNs. Taken together, our data suggest IFN and IFN are specialized IFNs that have evolved to weakly bind to the IFNAR2 chain, which allows innate protection of the mucosa and skin and limits neutralization of IFN and IFN biological activities by viral IFN antagonists.