Production of functional IL-18 by different subtypes of murine and human dendritic cells (DC): DC-derived IL-18 enhances IL-12-dependent Th1 development

IL-18 is a recently described cytokine that shares biological activities with IL-12 in driving the development of Th1-type T cells. As dendritic cells (DC) are very potent inducers of T cell proliferation and differentiation we wondered whether they utilize IL-18 as a factor driving Th1 development. We demonstrate by Northern blot and reverse transcription-PCR that various subtypes of human and murine DC as well as the DC-line XS contain IL-18 mRNA. When supernatants of either enriched Langerhans cells (LC) or bone marrow-derived DC were analyzed for production of IL-18 protein, IL-18 production was detected in an IL-18-specific ELISA. To assess whether the IL-18 protein released by DC is f…