| Immune cells constantly interact with their environment, receiving and integrating diverse cues that are required for proper function. The immune system has evolved specialized niches in which information transfer occurs between developing immune cells and their environment. The present understanding of the cells and signals involved in these interactions is based on several decades of work. With help from many experts in diverse fields of immunology, we have assembled an annotated list of classic papers that have identified those sites and the spatial organization and temporal ordering of those crucial immune cell signaling interactions. We gratefully acknowledge the following people for their help in selecting these landmark papers: Michael Cahalan, Rachael Caspi, Gerard Eberl, Bruno Kyewski, Tsvee Lapidot, Reina Mebius, Jacques Miller, Jerry Niederkorn, Susie Nilsson, Tannishtha Reya, Ellen Robey and Nancy Ruddle. |