Both populations express high levels of S100A8 and S100A9 that have been shown to greatly accumulate in MDSCs and are now recognized as one of the hallmarks of these cells.12 Consistently with RNA-seq data, S100A8+HLA-DRB1- MDSCs could be detected in neuroblastoma patient microbiopsies. This evidence concerns the gene S100A9 and neuroblastoma.