Interleukin-19 (IL-19) is a recently discovered member of the IL-10 family of Class II cytokines. Although it is known to be secreted by monocytes and has been associated with various models of disease, the biological function of IL-19 remains largely unknown. IL-19 does share many important characteristics with IL-10. Because of this, we hypothesized that IL-19 may be regulated in a manner similar to IL-10, and may provide insight into the molecular mechanism of IL-10 regulation. In addition, IL-19 has been reported to increase IL-10 production in monocytes, and we theorized that it may be able to do the same in macrophages. Like IL-10, IL-19 is expressed in regulatory macrophages. Also, IL-19 is itself able to increase IL-10 production in regulatory macrophages, and the mechanism is independent of ERK phosphorylation. This work suggests that IL-19 can play a central role in the anti-inflammatory processes of IL-10.