Training, memory, and tissue adaptation of NK cells and innate lymphoid cells

Innate lymphoid cells (ILCs) and natural killer (NK) cells can acquire durable functional changes following activation. These include features of trained immunity, such as epigenetic reprogramming and poised effector states, and of adaptive immune memory, including clonal-like expansion and acquired tissue residency. Together, these features enable adaptation of NK/ILC populations and their contributions to tissue homeostasis, immune surveillance, and secondary responses. Reciprocally, local niches are reshaped by inflammatory episodes, influencing immune cell behavior beyond resolution. Here, we discuss the layers of memory-like features in innate lymphocytes, highlighting emerging questions of NK/ILC differentiation and reprogramming, as well as their residency, interactions, and functions in tissues. We explore how immune experience modulates these processes, with implications for inflammatory diseases, vaccination, and immunotherapy.