Figure 1. Activation by IL-15 generates induced CD8α⁺ NK cells.

Cubitt et al. (11) present three scenarios for human NK cells responding to IL-15. (A) In the first scenario, CD8α⁺ NK cells receive an IL-15 signal and become sustained CD8α⁺ NK cells. (B) In the second scenario, CD8α^– NK cells with low expression of IL-15Rβ are activated by IL-15 and fail to upregulate CD8α, becoming persistent CD8α^– NK cells. (C) In the third scenario, CD8α^– NK cells with high expression of IL-15Rβ upregulate RUNX3 upon IL-15 stimulation and become induced CD8α⁺ NK cells. These cells exhibit several beneficial properties, including enhanced tumor control.