Fig. 3.

Model of the impact of NK cells on ALL development. a A prenatal preleukemic hit emerges in utero (red) and an expanded clone is present at birth. According to this model, interaction with NK cells plays a key role in leukemia development. HLA-C2 receptors (lavender) pose an elevated risk for ALL and can also interact with activating KIRs, e.g., KIR2DS1 [82]. An elevated number of activating KIRs (red), especially from the telomeric B cluster also pose a risk (right), whereas HLA-C1 (blue) and more inhibitory KIRs, i.e., the A-haplotype (green) seems to protect against ALL (left). b Scheme of NK cell killing efficiency and risk of developing ALL. NK cells with more inhibitory KIRs (green) have a higher killing efficiency and confer a lower risk of ALL; NK cells with more activating KIRs (red) have a lower killing efficiency and confer a higher risk of ALL