Flow Cytometric Detection of Angiopoietin Receptor Tie-2 in Acute Myeloid Leukemia

Background: Angiogenesis is required for the growth of solid tumors and hematologic neoplasia such as Acute Myeloid Leukemia (AML). Several endothelium-specific receptor tyrosine kinases (RTKs) such as TIE RTKs, Tie-1 and Tie-2, as well as, the vascular endothelial growth factor receptor kinases (VEGFRs) are known to play key roles in several important physiological and pathological angiogenesis. Objective and Methods: This study aims to investigate the expression of tyrosine kinase Tie-2 receptor in Acute Myeloid Leukemia by flow cytometry in 60 adult patients with newly diagnosed Acute Myeloid Leukemia (AML) and in 20 normal controls and correlate the angiogenic factor expression with other hematological variables and immunophenotyping. Results: According to the results of Tie-2 expression, AML patients were classified into 2 groups: high expression in 20 patients (33.3%), whereas 40 patients (66.7%) were designated as low expression. It was found that there was a highly significant difference between both groups as regarding Tie-2 expression (P<0.001). Moreover, there was a highly significant difference between the two patient groups as regarding age, WBC and Hb level (P<0.001) and a significant difference as regarding platelets` count and bone marrow blast cell count (P<0.05), while no significant difference as regarding gender. Tie-2 was highly expressed in M2 than M3 in low expression group. While, in high expression group, it was highly expressed in M5 than M1. A highly significant correlation was found between Tie-2 expression with WBC, bone marrow blast cell count and CD34 (P<0.001), a significant positive correlation with HLA-DR (P<0.05) and a highly significant negative correlation with both Hb levels and platelets` count. There was no correlation with CD13, CD14, CD33 and CD7. Conclusion: We concluded that elevated Tie-2 is a distinctive feature in Acute Myeloid Leukemia associated neo-angiogenesis and could be used as a prognostic factor to predict AML outcome.