Co-signaling molecules PD-L1, PD-1, LAG-3, CD40, CD86, CD27, CD70 and HVEM showed significantly different expression on primary pediatric ALL blasts (n≥10) as compared to physiologic CD19+CD10+ bone marrow cells, confirming inter-individual differences in immune escape of ALL blasts. Here, CD27 is linked to acute lymphoblastic leukemia.