The protein encoded by this gene is a cytokine that belongs to the IL-10 cytokine subfamily. This cytokine is found to be preferentially expressed in monocytes. It can bind the interleukin-20 receptor complex and lead to the activation of the signal transducer and activator of transcription 3 (STAT3). A similar cytokine in mouse is reported to up-regulate the expression of IL6 and TNF-alpha and induce apoptosis, which suggests a role of this cytokine in inflammatory responses. Alternatively spliced transcript variants encoding the distinct isoforms have been described.
^Chang C, Magracheva E, Kozlov S, Fong S, Tobin G, Kotenko S, Wlodawer A, Zdanov A (January 2003). "Crystal structure of interleukin-19 defines a new subfamily of helical cytokines". J. Biol. Chem.278 (5): 3308–13. doi:10.1074/jbc.M208602200. PMID12403790.