TY - JOUR AU - Rölle, Alexander AU - Pollmann, Julia AU - Ewen, Eva-Maria AU - Le, Vu Thuy Khanh AU - Halenius, Anne AU - Hengel, Hartmut AU - Cerwenka, Adelheid T1 - IL-12–producing monocytes and HLA-E control HCMV-driven NKG2C+ NK cell expansion PY - 2014/12/01/ AB - Human cytomegalovirus (HCMV) infection is the most common cause of congenital viral infections and a major source of morbidity and mortality after organ transplantation. NK cells are pivotal effector cells in the innate defense against CMV. Recently, hallmarks of adaptive responses, such as memory-like features, have been recognized in NK cells. HCMV infection elicits the expansion of an NK cell subset carrying an activating receptor heterodimer, comprising CD94 and NKG2C (CD94/NKG2C), a response that resembles the clonal expansion of adaptive immune cells. Here, we determined that expansion of this NKG2C+ subset and general NK cell recovery rely on signals derived from CD14+ monocytes. In a coculture system, a subset of CD14+ cells with inflammatory monocyte features produced IL-12 in response to HCMV-infected fibroblasts, and neutralization of IL-12 in this model substantially reduced CD25 upregulation and NKG2C+ subset expansion. Finally, blockade of CD94/NKG2C on NK cells or silencing of the cognate ligand HLA-E in infected fibroblasts greatly impaired expansion of NKG2C+ NK cells. Together, our results reveal that IL-12, CD14+ cells, and the CD94/NKG2C/HLA-E axis are critical for the expansion of NKG2C+ NK cells in response to HCMV infection. Moreover, strategies targeting the NKG2C+ NK cell subset have the potential to be exploited in NK cell–based intervention strategies against viral infections and cancer. JF - The Journal of Clinical Investigation JA - J Clin Invest SN - 0021-9738 DO - 10.1172/JCI77440 VL - 124 IS - 12 UR - https://doi.org/10.1172/JCI77440 SP - 5305 EP - 5316 PB - The American Society for Clinical Investigation ER -