Our research focuses on the development and functional specialization of macrophages (MΦs) and dendritic cells (DCs). To unravel the role of MΦs and DCs in the regulation of immune responses in vivo we have constructed novel DTR- or CRE- expressing knock-in mice that allow to deplete a particular MΦ or DC subset specifically in vivo or to knock-down genes of interests specifically within these cells. These novel knock-in mouse models include mice specific for liver resident Kupffer Cells and lung-resident Alveolar Macrophages. We are particularly interested in: (i) identifying the transcription factors that drive DC and MΦ development, (ii) unraveling how tissue-resident macrophages participate to the maintenance of tissue homeostasis and (iii) understanding how inflammation influences the development and function of DC and MΦ subsets.