An immune response to pathogen typically involves progression from inn
ate immunity to adaptive immunity. The questions of whether and how in
nate immunity influences adaptive immunity and vice versa are still la
rgely 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 imm
une response.