Characteristics Of Tim-3 Expression On NK Cells And Its Clinical Significance In Acute Myeloid Leukemia Patients

Objective: To explore whether Tim3/Galectin-9 pathway involved in immune escape in acute myeloid leukemia(AML), the characteristic of Tim-3 on natural killer(NK) cells as well as its ligands Glactin-9 expression on leukemia cells were investigated in patients with AML.Methods: Clinical data of 39 patients diagnosed with AML by bone marrow MICM classification as well as 29 healthy volunteers were collected. Anticoag lated peripheral blood(5ml) before any treatment was taken from each candidate for futher in vitro experiments. CD3, CD56 and Tim-3 expression levels on NK cells from both groups were detected by immunofluorescence labeling followed by flow cytometry. Galetin-9 expressions on leukemia cells of peripheral blood in AML patients were detected by real-time PCR.Results: First, we found that the ratio of the peripheral blood CD3-CD56+NK cells in newly diagnosed AML patients were significantly decreased compared to that of normal control,(5.73±4.30)% vs(12.55±6.33)%, P<0.005. Second, the ratio of NK cells in AML patients with complex chromosome karyotype was significantly decreased,(4.83±2.83)% vs(10.04±6.51)%, P=0.006.Third,Tim-3 expression levels on the peripheral blood NK cells in AML patients were significantly decreased compared to that of normal control(42.61±19.08)% vs(60.99±20.69)%,P<0.005.Fourth,Tim-3 expression levels on the peripheral blood NK cells in CR patients were significantly decreased compared to that of PRor NR(42.77±23.87)% vs(32.82±20.13)%,P=0.05. Fifth, the lower expression level of Tim-3 on NK cells of the peripheral blood in moderately or high risk cases compared to that of low risk cases,(43.57±19.60)% vs(33.85±23.336)%,P=0.05. sixth, Galectin-9 expression levels in AML patients were higher that in healthy candidates, however there was no significance between two groups,P=0.891.Conclusion: Compared to healthy control, lower proportion of NK cells and lower expression levels of Tim-3 were detected in AML patients, which were also found to be related to poor prognosis. Galectin-9 expression levels were up-regulated in AML patients. The results suggested that Tim-3/Galectin-9 pathway may be involved in the immune escape of AML cells through downregulating the immune response of NK cells.