The presence of regulatory T cells (Treg) in NB tumors has not been reported but MYCN amplification in NB tumors correlates with a higher number of CD4+/CD25hi/CD127-Treg cells in bone marrow (BM) and of CD4+/CD45R0+/CD49b+/LAG3+ type 1 regulatory T (Tr1) cells in peripheral blood (PB) of patients [39]. Here, CD4 is linked to neuroblastoma.