Quantitative Expression of Toll-Like Receptors TLR-7 and TLR-9 on Peripheral Blood Mononuclear Cells in Leukemias

Background: Toll-like receptors (TLRs) are agents of innate and adaptive immunity, involved in tumor activation. The expression and functionality of TLR on leukemic cells have seldom been investigated. The aims of the study were to throw some light on the quantitative expression of TLR-7 and TLR-9 on leukemic cells and to compare it with their expression on mononuclear cells of healthy volunteers. Methods: Ninety subjects were included: 30 acute leukemia, 30 chronic leukemia, and 30 healthy controls. Peripheral blood mononuclear cells (PBMCs) were isolated, and the expressions of TLR-7 and 9 were detected by real-time PCR. Results: Expression of TLR-7 in acute leukemia was significantly higher than normal controls, while TLR-9 did not show significant difference. TLR-7 and TLR-9 expression in chronic myeloid leukemia (CML) was significantly lower than normal controls. Expression of TLR-7 and TLR-9 in chronic lymphocytic leukemia (CLL) was significantly higher than normal controls. Conclusion: Although TLR-7 and TLR-9 could be expressed in acute leukemia cells, only TLR-7 shows significantly different expression with controls, indicating that TLR-7 may play a role in the immune escape from acute leukemia which suggests a potential role for TLR-7 agonists in immunotherapy. The mRNA expressions of TLR-7 and TLR-9 are significantly reduced in CML patients, which may be the main reason of function defects of PBMCs. The mRNA expressions of TLR-7 and TLR-9 are significantly increased in CLL. This might prove relevant for elucidating the immune mechanisms underlying CLL and define subgroups of patients who might benefit from treatment with specific TLR-7 and TLR-9 ligands. J Hematol. 2016;5(1):17-24 doi: http://dx.doi.org/10.14740/jh249w