IL-11 was discovered in 1990 and first described as a hematopoietic factor that stimulates plasmacytoma proliferation and megakaryocyte formation. The dependence of IL-11 on the ubiquitously expressed receptor gp130 designates IL-11 as a member of the IL-6 family of cytokines. IL-6 family cytokines have been shown to bind to gp130 alone, although the accepted mode of signaling requires the interaction of cytokines with a specific, high-affinity receptor subunit (alpha chain) prior to binding to gp130. The gp130 receptor subsequently triggers a number of different pathways, including canonical JAK/STAT signaling, as well as ERK and AKT Loss-of-function mutations in IL-6 family cytokines or receptors result in a diverse set of genetic disorders of varying severity, which suggests nonredundant and distinct biological functions of members of this cytokine family. In the lung, IL-11 receptor subunit alpha (IL11RA) is highly expressed on cells such as fibroblasts, vascular smooth muscle cells, and epithelial cells. These cell types are central for both acute and chronic diseases of the lung/respiratory tract. This receptor expression pattern differentiates IL11RA from the IL-6 receptor, which is most highly expressed on immune cells, including monocytes and tissue-resident macrophages.