Phenotypical Characterization of Cells in the Thoracic Duct of Patients with and without Systemic Inflammatory Response Syndrome and Multiple Organ Failure

The subset composition and recirculation properties of the migrating lymphocyte pool in humans is largely unknown. The present study was conducted in order to phenotypically characterize cells in human thoracic duct lymph of patients under non-inflammatory and inflammatory conditions. These data were compared with data from peripheral blood, with special emphasis on those cells homing to the gut. Thoracic duct lymph and peripheral blood contained comparable proportions of B and T lymphocytes and CD8⁺ cells. Thoracic duct lymph contained proportionally more CD4⁺ cells, more CD4⁺CD45RO⁺ that express α₄β₇ cells and more CD8⁺CD45RO⁺ that express α₄β₇, as compared to peripheral blood. These data suggest an equal recirculation rate of B and T lymphocytes; a more active recirculation of CD4⁺ cells compared to CD8⁺ cells; and a more active recirculation of memory cells to the gut as compared to other extra-lymphoid sites in patients under non-inflammatory conditions. Data were also obtained in patients with the system inflammatory response syndrome and multiple organ failure. Although it is generally assumed that granulocytes and monocytes do not recirculate, lymph of multiple organ failure patients contained significantly more granulocytes than monocytes, indicating that in severe generalized inflammatory states these cells re-enter the circulation through the thoracic duct. Furthermore, no increased activation of cells homing to the gut was found in these patients.