Reduced Granulocyte Activation with a Heparin–Coated Device in an In Vitro Model of Cardiopulmonary Bypass

Granulocyte activation during cardiopulmonary bypass (CPB), resulting in degranulation, may have adverse effects. Fresh whole human blood and priming solution was circulated through oxygenator/tubing sets coated with functional heparin (n = 7) and through uncoated sets (n = 7) in model CPB. Plasma concentrations of the primary granule protein myeloperoxidase (MPO) and the secondary granule protein lactoferrin (LF) were measured in radioimmunoassays, and the neutrophils were counted. After 120 min, seven to nine times baseline concentrations of LF (p less than 0.0001) were observed with both devices. Increases of MPO were also significant, but significantly larger (p less than 0.01) with the uncoated devices. There was an equivalent reduction in neutrophil numbers in both groups. MPO did not bind to heparin-coated Sephadex particles in gel chromatography. Thus, the heparin coating most likely prevented the release of potentially harmful primary granule proteins, indicating improved biocompatibility. Adhesion of neutrophils and exocytosis of LF, which may be involved in adhesion, were unaffected.