CX3CR1 and neuroblastoma: Increased CXCR3 and reduced CX3CR1 expression was observed also in peripheral blood NK cells of stage 4 neuroblastoma patients, and it may represent an attempt to avoid NK cell cytolytic subset recruitment to the tumor site, while promoting the enrichment of immature and poorly cytotoxic CD56high subset in tumor leukocyte infiltrates (55, 56).