Interferon-gamma critically determines dendritic cell function

A growing body of evidence suggests that inflammatory cytokines have a dualistic role in immunity. In this study, we sought to determine the direct effects IFN-gamma on the differentiation and maturation of human peripheral blood monocyte-derived dendritic cells (moDC). Here, we report that following differentiation of human peripheral-blood monocytes into moDCs with granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-4, interferon-gamma (IFN-gamma) induces moDC maturation and up-regulates the co-stimulatory markers CD80, CD86, CD95, and MHC Class I, enabling moDCs to effectively generate antigen-specific CD4+ and CD8+ T cell responses for multiple viral and tumor antigens. Interestingly, early exposure of monocytes to high concentrations of IFN-gamma promotes monocyte differentiation into macrophages, despite the presence of GM-CSF and IL-4. However, under low concentrations of IFN-gamma, monocytes continue to differentiate into dendritic cells possessing a unique gene-expression profile, resulting in impairments in subsequent maturation by IFN-gamma and an inability to generate effective antigen-specific CD4+ and CD8+ T cell responses compared to standard moDCs. Monocytes differentiated in the presence of low levels of IFN-gamma downregulate IFN-gamma receptor expression, impairing their response to an inflammatory rechallenge. These findings demonstrate the ability of IFN-gamma to impart differential programs on human moDCs which shape the antigen-specific T cell responses they induce. Timing and intensity of exposure to IFN-gamma can thus determine whether moDCs are tolerogenic or immunostimulating.

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Kerkar SP, Chinnasamy D, Hadi N, Melenhorst J, Muranski P, Spyridonidis A, Ito S, Weber G, Yin F, Hensel N, Wang E, Marincola FM, Barrett AJ