CCL19 and acute lymphoblastic leukemia: To explore the clinical significance of immature DC in human ALL, a DC maturation-associated gene set, including CCL19, CCL21, CCR7, CD209, CD40, CD80, CD83, CD86, HLA-DMB, HLA-DRA1, HLA-DRB1, HLA-DQB1 and RELB, was defined based on the reports [39–43] (Supplementary Table S3).