Interleukin 17D is a cytokine that shares the sequence similarity with IL17. The treatment of endothelial cells with this cytokine has been shown to stimulate the production of other cytokines including IL6, IL8 and CSF2/ GM-CSF. The increased expression of IL8 induced by this cytokine was found to be NF-kappa B-dependent.The predicted 202-amino acid protein, the longest in the IL17 family, contains a signal peptide, conserved cysteines that allow homodimer formation, and a unique extended C-terminal domain. RT-PCR analysis showed high expression in skeletal muscle, brain, adipose, heart, lung, and pancreas, with lower expression in bone marrow, fetal liver, kidney, leukocytes, liver, lymph node, placenta, spleen, thymus, tonsil, resting CD4 -positive T cells, and resting CD19 -positive B cells.