In this study, we have used transcript profiling with microarrays and chromatin immunoprecipitation (ChIP) hybridization on genomic DNA arrays (ChIP-chip) in macrophages from normal and IRF8-deficient mice, to systematically identify genes transcriptionally regulated by IRF8 a) during ontogeny and maturation of macrophages, and b) in response of these cells to combined exposure to IFNγ and Tlr9 (Toll-like receptor 9) ligand (CpG), and c) during pulmonary tuberculosis in vivo. This evidence concerns the gene TLR9 and pulmonary tuberculosis.