Immune regulation: A critical link between NK cells and CTLs

An immune response to pathogen typically involves progression from innate immunity to adaptive immunity. The questions of whether and how innate immunity influences adaptive immunity and vice versa are still largely unexplored. Here, Ferdynand Kos and Edgar Engleman propose that natural killer (NK) cells and cytotoxic T lymphocytes (CTLs) regulate the functions of each other, thereby controlling the outcome of an immune response.