CD8A and congenital rubella syndrome: While IL-15 strategies have already been implemented in clinical studies of CAR-NK products [46,49,50,52], it remains important to thoroughly investigate the safety of supplementary cytokine approaches in such clinical candidates, since IL-15 may increase the risk of CRS (albeit apparently more so with conventional CAR-T rather than CAR-NK) [88], as well as having CD8+ T cell-activating properties that may accelerate allorejection [117].