Innate lymphoid cells—Underexplored guardians of immunity

NK cells and ILC1s-Two sides of the same coin?Although NK cells and ILC1s arise from a common lymphoid progenitor [2], both express IFN-γ and both are implicated in the early clearance of intracellular pathogens [27].Especially human NK cells are phenotypically difficult to distinguish from ILC1s due to their overlapping surface receptor expression, such as NKp46, NK1.1 (mouse), CD56 (human) [6,27] (Fig 1), and owing to a lack of unique, subset-defining hallmarks.The NK lineage commitment is initiated by Eomesodermin (Eomes), whereas ILC1 up-regulates T-bet instead, along with surface receptors such as IL-7Rα, CD90, CD49a, and CD200r1 [6,21,28,29] (Fig 1).Expression of these subset markers may differ depending on their