At the 38th Annual Meeting of the Society for Leukocyte Biology held in Oxford this year, the biology of dendritic cells (DCs) and macrophages was discussed. In particular, functional genomics approaches were presented to investigate transcriptional changes during microbe and phagocytes interactions. Here, we report functional genomics studies likely to be of interest to the Journal of Leukocyte Biology readers with a particular emphasis on DC biology. DCs are professional antigen-presenting cells, which are essential for the initiation and regulation of natural killer, T, and T regulatory cell responses. Immature DCs, resident in peripheral sites, are specialized in antigen capture and continually sample soluble and particulate antigens in their local environment. DCs express receptors for cytokines, chemokines, endogenous danger signals, and microbial structures. The interactions between DCs and microorganism are complex, but progress in the past few years has shed light on several aspects of these processes. Infectious disease is the result of an intimate relationship between pathogens and hosts. Thus, understanding the cross-talk between host and pathogen is essential to improve our knowledge of infectious disease. Functional genomics and proteomics applied to DCs and macrophage biology are now providing powerful tools to dissect, at the molecular level, host-pathogen interactions.