As the most common pediatric malignancy, the B-cell precursor acute lymphoblastic leukemia (BCPALL) expresses detectable alterations in costimulatory molecule expression of TLR2, TLR7, and TLR9, being TLR2 ligands PAM3CSK4 and PGN, the most powerful effect on anti-ALL immune responses (212). Here, TLR2 is linked to acute lymphoblastic leukemia.