Increased angiogenesis and Fas-ligand expression are independent processesin acute myeloid leukemia

We evaluated the clinical significance of tumor angiogenesis and Fas-ligand (FasL) expression using parameters including the microvessel. count (MVC), vascular endothelial growth factor (VEGF) level, and FasL expression in pa tients with acute myeloid leukemia (AML). Paraffin-embedded bone marrow (BM ) sections from 43 AML patients at diagnosis, 20 patients after subsequent induction therapy, and 18 controls with non-invasive lymphoma were stained immunohistochemically for von Willebrand factor (vWF) and FasL. VEGF in BM mononuclear cells from 32 AML patients at diagnosis and 10 controls, includ ing bone marrow transplantation donors, was assayed by an ELISA method. We found that the mean MVC, VEGF level, and FasL expression in AML patients at diagnosis were significantly higher than those of controls, with a signifi cant correlation between the MVC and VEGF levels (r = 0.43). However, there were no correlations between FasL expression and MVC or VEGF level. The me an MVC and FasL expression after induction therapy were lower than those ev aluated at diagnosis, but were higher than those of controls. There was a c orrelation between the MVC and percentage of BM blasts (r = 0.479), but no correlation between the MVC, VEGF level, or FasL expression and other hemat ologic or clinical variables. Our findings provide evidence of increased an giogenesis and tumor immune escape in AML, and both angiogenesis and tumor immune escape are independent processes in AML. (C) 2001 Elsevier Science L td. All rights reserved.