Hepatic microcirculation in murine sepsis: role of lymphocytes.

Sepsis is a leading cause of death in pediatric intensive care units. There is growing evidence that lymphocytes play a pivotal role in mediating the microvascular dysfunction during sepsis. The objective of this study was to define the role of different subsets of lymphocytes in mediating the hepatic microvascular alterations elicited by cecal ligation and puncture (CLP), an experimental model of sepsis. Intravital video microscopy was used to quantify leukocyte and platelet adhesion in the hepatic microcirculation of wild type (WT) mice, immunodeficient SCID mice, SCID mice reconstituted with CD3+ cells, and mice deficient either in B-cells, CD4+- or CD8+-T-cells subjected to CLP. Blood cell counts, and serum concentrations of ALT and different cytokines (TNF-alpha, IL-10, MCP-1, IL-6, IFN-gamma and IL-12) were also monitored in these groups. CLP (at 6 h) caused a significantly increased adhesion of leukocytes and platelets in WT mice, compared to WT sham mice (P < 0.05). In SCID mice, the adhesion of blood cells in terminal hepatic venules was significantly decreased compared to WT-CLP mice, whereas the values in CD3+ cell-reconstituted SCID-mice, B-cell-deficient and CD4+- and CD8+-T-cell deficient mice did not differ from WT-CLP mice. ALT levels were significantly elevated only in the SCID group, when compared to WT-sham and WT-CLP mice. These findings indicate that lymphocytes mediate the microvascular dysfunction, but protect against the hepatocellular injury associated with murine sepsis.