Furthermore, coculture studies with human umbilical vein endothelial cells showed that human umbilical vein endothelial cells protected chronic lymphocytic leukemia cells from spontaneous apoptosis by direct cell-to-cell contact as assessed by flow cytometry using annexin V. Our data suggest that constitutively activated signal transducer and activator of transcription 3 induces vascular endothelial growth factor production by chronic lymphocytic leukemia cells and that chronic lymphocytic leukemia cells derive a survival advantage from endothelial cells via cell-to-cell contact.
Fifty-five cases with B-cell neoplasms of acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), hairy cell leukemia (HCL), B-cell malignant lymphoma (ML), and myeloma (MM) were studied for qualitative and quantitative expression and function of Fas using flow cytometry and annexin-V staining methods.