IL-28 is a family of cytokines that belongs to interferons termed as λ-interferons or type III interferons （IFN）. This family includes IL-28A（IFN-λ2）, IL-28B（IFN-λ3） and IL-29（IFN-λ1） in human and IL-28A and IL-28B in mice. IL-28A, IL-28B and IL-29 share a unique heterodimeric receptor IFNLR consisting of IL-28Rα and IL-10R, which is mainly expressed by epithelial cells, dendritic cells （DCs） and macrophages. IL-28B inhibits M2 macrophage polarization in vitro, while also halting M2 macrophage differentiation predominantly via inhibition of the signal transducer and activator of transcription （STAT）3 and c-Jun N-terminal kinase （JNK） signaling pathways. Results reveal a protective role of IL-28B via regulation of epithelial cells in protease induced asthma.