Effect of heating on extracellular bioactive substances in stored human blood: In vitro study

Background: We have previously shown extracellular accumulation of various leukocyte and platelet-derived bioactive substances in human blood during storage. Release of bioactive substances may be temperature-dependent, and we studied the effect of heating during in vitro transfusion on bioactive substance accumulation in stored human blood. Methods: Eight units of whole blood and eight units of prestorage leukofiltered whole blood were stored at 4 degrees C for 7 days. Subsequently, the blood from all 16 units was transfused via a blood-heating device, which increased the blood temperature to 37 degrees C at outlet. Samples for enzyme-linked immunosorbent assay or radioimmunoassay analyses of histamine, myeloperoxidase (MPO), eosinophil cationic protein (ECP), and plasminogen activator inhibitor-1 (PAI-1) were drawn from the units at donation, after 7 days of storage just before transfusion, and during the in vitro transfusion. Results: Extracellular concentrations of histamine, MPG, ECP, and PAI-1 were significantly (p < 0.05) increased in nonfiltered whole blood stored for 7 days compared with concentrations in fresh donated blood and in prestorage leukofiltered whole blood stored for 7 days. Heating reduced histamine, MPO, and ECP concentrations significantly (p < 0.05) in nonfiltered whole blood, whereas PAI-1 concentrations increased significantly (p < 0.05). Finally, there was no difference in concentrations of histamine, MPO, ECP, and PAI-1 in samples collected before and after heating of leukofiltered whole blood. Conclusions: Heating reduces accumulation of extracellular leukocyte-derived bioactive substances in whole blood, whereas it increases platelet-derived substances. Prestorage leukofiltration, however, reduces the obligatory extracellular accumulation of leukocyte and platelet-derived bioactive substances, which in addition is unchanged by heating.