HLA-E and neuroblastoma: As shown in Figure 1, plasma levels of sHLA-E ((a) arbitrary units/mL ± SD; HC: 0.07 ± 0.02, NB 0.2 ± 0.08, P < 0.0001), sHLA-F ((b) arbitrary units/mL ± SD; HC: 0.1 ± 0.03, NB 0.76 ± 0.33, P < 0.0001), chromogranin ((c) pg/mL ± SD; HC: 1.4 ± 0.63, NB 6.47 ± 10.41, P < 0.0001), and calprotectin ((d) ng/mL ± SD; HC: 3.57 ± 2.76, NB 71.11 ± 120.2, P < 0.0001) were significantly higher in NB patients than in HC.