Since most of studies investigating cytokine levels during human orthotopic liver transplantation used venovenous bypass (VVB), it may be difficult to distinguish between the increase in proinflammatory mediators induced by VVB, by ischemia-reperfusion injury or by splanchnic venous congestion in the anhepatic phase. The goal of this investigation was to assess the levels of interleukin-6 (IL-6) and soluble interleukin-2 receptors (sIL-2r) during OLT procedures routinely performed without VVB.
Patients and methods: Twenty-one consecutive patients underwent OLT with cross clamping of the inferior caval vein without VVB. Soluble IL-2r concentrations were measured by means of luminescence enzyme immunometric assay and IL-6 by means of a sequential immunometric assay. Time points (TP) of sampling were before induction of anesthesia (TP1), after cross-clamping of the inferior vena cava (TP2), 15 minutes after reperfusion (TP3), and 24 hours after the transplant procedure (TP4).
Results: Soluble IL-2r increased significantly 24 hours after transplantation (P =.02) compared to TP1, TP2, and TP3. IL-6 increased significantly during the anhepatic period (TP2 vs TP1, P =.003) and again in the reperfusion period (TP2 vs TP3, P =.002). Twenty-four hours after surgery IL-6 declined significantly (TP3 vs TP4, P =.001), but remained significantly higher (P = 0.04) compared to TP1. Furthermore, we examined the relative changes (DeltaTP %) in perioperative levels of cytokines compared with those previously published in studies using VVB. We observed higher values of DeltaTP % of IL-6 in TP2 and TP4 among our group of patient without VVB. The data on sIL-2r were similar, suggesting no major effects of the operative technique on sIL-2r levels.
Conclusion: The two interleukins showed different perioperative trends. Our data suggest that cross clamping contributes more to cell activation, namely, increased release of IL-6 in the anhepatic phase than the use of VVB. However, no major differences were observed during the reperfusion period. The extent of clinical effect on graft function of higher IL-6 levels in the anhepatic period among recipients not supported with VVB remains to be clarified.