The present invention concerns a novel human cytokine. In particular, isolated nucleic acid molecules are provided encoding interleukin-19 (IL-19). IL-19 polypeptides are also provided, as are vectors, host cells and recombinant methods for producing the same. The IL-19 polypeptides of the present invention can also be used to raise polyclonal and monoclonal antibodies. The invention further concerns therapeutic methods for modulating cytokine production.