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L-selectin expression increases on peripheral blood polymorphonuclear leukocytes during active marrow release
S Van Eeden1, R Miyagashima, L Haley
1Pulmonary Research Laboratory, University of British Columbia, St. Paul's Hospital, Vancouver, Canada.
Abstract:
The cell adhesion molecule L-selectin is highly expressed on mature bone marrow polymorphonuclear leukocytes (PMN), and the release of these cells from the bone marrow could produce a population of circulating PMN expressing high levels of L-selectin. Because L-selectin initiates the interaction of PMN with activated endothelium, these cells could be important in the pathogenesis of multiorgan failure following sepsis and septic shock. The present study was designed to test the hypothesis that the release of PMN from the bone marrow increases the expression of L-selectin on circulating PMN. Peripheral blood and bone marrow samples were obtained immediately after sternotomy (BM1) and during (BM2) and just before closing the sternum (BM3) in five normothermic and five hypothermic cardiopulmonary bypass (CPB) procedures. L-selectin was measured using both immunocytochemistry and flow cytometry. The results showed that L-selectin expression on bone marrow PMN was greater than on peripheral blood PMN (p < 0.01) in all patients at baseline. Bone marrow release of PMN during normothermic CPB was associated with a rise in peripheral blood band cells (0.18 +/- 0.7 versus 0.56 x 10(9)/L) (p < 0.01) and an increase in the percentage of PMN expressing high levels of L-selectin (9 +/- 3.3 to 36 +/- 6.6%, p < 0.03) and the L-selectin mean fluorescence intensity (MFI) on PMN (p < 0.05). The expression of L-selectin on band cells was higher than on segmented PMN in the circulation (p < 0.01). Hypothermia (27 degrees C) prevented the release of band cells into the circulation and the increased expression of L-selectin on the PMN.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Bone marrow release of polymorphonuclear leukocytes (PMN) during surgery increases L-selectin expression on circulating PMN. Hypothermia during cardiopulmonary bypass prevents this L-selectin upregulation, potentially impacting sepsis pathogenesis.
Area of Science:
- Immunology
- Cell Biology
- Surgical Science
Background:
- L-selectin, a cell adhesion molecule, is highly expressed on bone marrow polymorphonuclear leukocytes (PMN).
- Increased L-selectin on circulating PMN may contribute to multiorgan failure following sepsis and septic shock.
- The release of PMN from bone marrow into circulation is a key factor to investigate.
Purpose of the Study:
- To test the hypothesis that PMN release from bone marrow increases L-selectin expression on circulating PMN.
- To investigate the role of L-selectin in PMN trafficking during cardiopulmonary bypass (CPB).
- To determine the effect of normothermic versus hypothermic CPB on L-selectin expression.
Main Methods:
- Peripheral blood and bone marrow samples were collected during CPB procedures.
- L-selectin expression was quantified using immunocytochemistry and flow cytometry.
- Comparison of L-selectin levels on PMN in normothermic and hypothermic conditions.
Main Results:
- Baseline L-selectin expression was higher on bone marrow PMN than peripheral blood PMN.
- Normothermic CPB increased circulating band cells and elevated L-selectin expression and MFI on PMN.
- L-selectin expression was higher on band cells than segmented PMN; hypothermia inhibited these changes.
Conclusions:
- Bone marrow PMN release during normothermic CPB significantly upregulates L-selectin on circulating PMN.
- Hypothermia during CPB mitigates the release of PMN and subsequent L-selectin upregulation.
- Findings suggest a mechanism linking CPB conditions to PMN activation and potential inflammatory responses.