While PD-L1 was absent on the surface of all NB cell lines, 5 out of 6 MYCN-amplified NB cell lines showed baseline expression of HLA-ABC that was comparable to the non-MYCN amplified cell lines (Supplemental Figure 1A; supplemental material available online with this article; https://doi.org/10.1172/JCI175310DS1). This evidence concerns the gene CD274 and neuroblastoma.