Bacteria-induced release of white cell- and platelet-derived vascular endothelial growth factor in vitro

Background and Objectives Poor prognosis after resection of primary colorec tal cancer may be related to the combination of perioperative blood transfu sion and subsequent development of infectious complications. White blood ce ll- and platelet-derived cancer growth substances, including vascular endot helial growth factor (VEGF), may be involved in this process. Therefore, we studied the in vitro release of VEGF from white blood cells and platelets stimulated by bacterial antigens and supernatants from stored red cell comp onents. Materials and Methods Eight units of whole blood (WB) and eight units of bu ffy-coat-depleted red cell (SAGM) blood were donated by healthy blood donor s. Subsequently, half of every unit was leucocyte depleted by filtration, a nd all 32 half-units were stored under standard conditions for 35 days. Jus t after storage, and on days 7, 21 and 35 during storage, aliquots of the s upernatants were removed from the units and frozen at -80 degreesC. WB from other healthy donors was stimulated for 2 h with sodium chloride (controls ), with Escherichia coli lipopolysaccharide (LPS) alone, or with LPS plus s upernatants from the non-filtered or prestorage leucofiltered WB units (dil uted 1 : 10), or from non-filtered or prestorage leucofiltered SAGM blood u nits (diluted 1 : 20) stored for 0, 7, 21, or 35 days, respectively. Simila r assays were performed using Staphylococcus aureus-derived protein A as a stimulatory antigen. The concentration of VEGF was determined in supernatan ts from stored blood and in assay supernatants by using enzyme-linked immun osorbent assay (ELISA). Results The concentration of VEGF increased significantly (P < 0.0001) in a storage time-dependent manner in non-filtered WB and SAGM blood, while the increase was abrogated by prestorage leucofiltration. The supernatant conc entration of VEGF was significantly increased in LPS-stimulated (P = 0.002) and in protein A-stimulated (P < 0.0001) assays compared with controls. Ad dition of supernatants from stored, nonfiltered WB or SAGM significantly in creased the assay supernatant VEGF concentration storage-time dependently ( P = 0.006) in LPS assays. In protein A assays, only supernatants from non-f iltered WB significantly increased the assay supernatant VEGF concentration storage-time dependently (P = 0.022). This additional effect by supernatan ts from stored blood components was not observed with prestorage leucofilte red blood. Conclusions Extracellular VEGF may accumulate in non-filtered red cell comp onents, but this can be prevented by prestorage leucocyte depletion using f iltration. In addition, bacterial antigens appear to induce release of VEGF from white blood cells and platelets. Addition of supernatants from stored , non-filtered WB or SAGM blood may increase the VEGF levels in a storage t ime-dependent manner, while prestorage leucofiltration may prevent further increase by supernatants.