The concentrations of vascular endothelium growth factor and angiogenin were measured by enzyme immunoassay in the sera of healthy subjects and patients with osteosarcoma and Ewing's tumor with consideration for the main clinical and morphological characteristics of the diseases. The studied angiogenic factors were characterized by high individual variability in both healthy subjects and age- and sex-matched patients with primary bone sarcomas. The level of endothelial growth factor was higher in control women than in men. The highest concentration of endothelial growth factor was detected in male patients with Ewing's tumor. Possible involvement of vascular endothelium growth factor and angiogenin in the pathogenesis of osteosarcoma and Ewing's tumor is discussed.

Serum levels of sRANKL, RANK, OPG, IL-8, IL-6, IL-16, MMP-2, and calcitonin were measured by ELISA in patients with malignant, borderline, and benign bone tumors and in healthy individuals (control). Serum levels of RANK, OPG, IL-8, IL-6, and the OPG/sRANKL ratio were significantly higher, while the level of MMP-2 was significantly lower in patients with bone tumors than in controls. Serum concentration of IL-16 in osteosarcoma patients was significantly lower than in chondrosarcoma patients. No significant differences between bone sarcomas of different differentiation were detected for any of the studied markers. Calcitonin level depended on the tumor location and type.

Blood concentration of soluble Fas antigen is higher in patients with benign and malignant tumors in comparison with healthy subjects, which probably suggests its involvement into tumorigenesis. Key Words: tumors; apoptosis; soluble Fas antigenApoptosis, programmed cell death, is an important mechanism maintaining homeostasis in multicellular organisms. Disturbances in cell elimination underlie various pathological states such as malignant tumors, Alzheimer disease, multiple sclerosis, amyotrophic lateral sclerosis, thyroiditis, hepatitis, and autoimmune diseases.Fas/APO-1/CD95 is a type I transmembrane glycoprotein belonging to the TNF/NDF receptor family [5]. Fas is expressed in various tissues, in particular in the thymus, liver, heart, lungs; it is present on activated lymphocytes, natural killers, virus-infected and tumor cells.Similarly to tumor necrosis factor p55, Fas not only induces cell apoptosis upon interaction with specific ligand FasL or agonistic monoclonal antibodies (MCA) to Fas, but also activate transcription factor NtkB [14]. The mechanism triggering cell death via Fas is studied in detail. The interaction of Fas with FasL or agonistic MCA induces activation of caspase-8 or caspase-2 proteases via adapter proteins FADD/ MORT-1 or RIP and RAIDD, respectively [11,14] Molecular cloning studies and nucleotide-sequence analysis have demonstrated that apart from transmembrane Fas receptor, cells produce also soluble Fas (sFas), a product of alternative spicing of full-length Fas mRNA, which inhibits cytotoxicity induced by anti-Fas MCA in vitro [2,3]. Thus, enhanced production of sFas can underlie cell resistance to apoptosis.Elevated blood concentration of sFas was observed in some autoimmune disease: systemic lupus erythematosus [15] The aim of the present study was to determine serum concentration of sFas in patients with malignant tumors of various morphology and localization and to explore the relationship between sFas and these diseases. MATERIALS AND METHODSHybrid cells producing MCA to recombinant full-length Fas (Coultronics) were obtained according to a standard protocol [9]. Splenocytes from immunized BALB/c mice (3 intraperitoneal injections with a 2-week interval) were fused with mouse myeloma cells NSO/1