Through the use of powerful genomic techniques, researchers at the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) have found that the development of immune cells, called innate lymphoid cells (ILCs), gradually prepares these cells for rapid response to infection. This work, which appeared online today in Cell, sheds light on the development and function of a cell type that is increasingly recognized as having an important role in the body’s immune defense. NIAMS is part of the National Institutes of Health.