IL-17D is a disulfide-linked homodimer of two 185 amino acid polypeptide chains. It belongs to the IL-17 family of structurally-related cytokines that share a highly conserved C-terminal region but differ from one another in their N-terminal regions and in their distinct biological roles. The six known members of this family, IL-17A through IL-17F, are secreted as homodimers. IL-17D has the ability to stimulate the production of IL-6, IL-8, and GM-CSF and inhibits hemopoiesis of myeloid progenitor cells in colony forming assays. Recombinant human IL-17D is a 40.5 kDa disulfide-linked homodimer of two 185 amino acid polypeptide chains.