CD4 and neuroblastoma: Treg cells with a CD3+, CD4+, CD25+, Foxp3+ immunophenotype have not yet been investigated in NB patients; however, pre-clinical data from immunocompetent mice bearing syngeneic tumors indicate that in vivo depletion of Treg cells augments the efficacy of anti-NB vaccines and confers long term anti-tumor immunity mediated by CD8+ T cells (Croce et al., 2010; Jing et al., 2011).