Mannose-binding lectin is involved in multiple organ dysfunction syndrome after cardiac surgery: effects of blood transfusions

BACKGROUND: Serum levels of mannose-binding lectin (MBL), a recognition molecule of the lectin pathway of complement, are highly variable, based on genetic variation. After cardiac surgery, extracorporeal circulation and ischemia-reperfusion injury initiate a systemic inflammatory response, which can evolve to multiple organ dysfunction syndrome (MODS). Preoperative transfusions of allogeneic white blood cells (WBCs) contribute to infectious and inflammatory complications. This study investigates the role of MBL in relation to blood transfusions and complications after cardiac surgery. STUDY DESIGN AND METHODS: In cardiac surgery patients who participated in a randomized trial comparing leukoreduced with buffy coat-depleted red blood cell (RBC) transfusions, circulating MBL was measured pre- and postoperatively by enzyme-linked immunosorbent assay (ELISA). Data were related to the incidence of complications and to the transfusions the patients received. RESULTS: Patients with high preoperative serum MBL levels (> 400 ng/mL) show a significant (52 +/- 12%) decrease of serum MBL postoperatively, whereas patients with low serum MBL levels (<= 400 ng/mL) show a significant increase of serum MBL levels after surgery (140 +/- 106%), which was further enhanced by fresh-frozen plasma (FFP) transfusions. MBL levels were not associated with infections, sepsis, or death. Patients with MBL deficiency (MBL <= 80 ng/mL) were protected against development of MODS (p = 0.016), whereas FFP transfusion abolished this protection (p = 0.048). CONCLUSION: Cardiac surgery is associated with MBL consumption, independent of the transfusion of allogeneic WBCs. Patients with MBL deficiency develop no MODS, unless they have been transfused with FFP, which is associated with MBL reconstitution. Therefore, sustained MBL deficiency may be a favorable status for patients undergoing cardiac surgery.