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Updated: Aug 22, 2026
Analysis of Physiologic E-Selectin-Mediated Leukocyte Rolling on Microvascular Endothelium
Published on: February 11, 2009
L-selectin and chemotaxis throughout bone marrow granulocyte maturation in the bovine
E Monfardini1, V Van Merris, M Paape
1Department of Physiology, Biochemistry, and Biometrics, Faculty of Veterinary Medicine, University of Ghent, Salisburylaan, 133, Merelbeke 9820, Belgium.
Abstract:
Polymorphonuclear neutrophilic leukocytes (PMNL) play a pivotal role during inflammation. Bone marrow (BM) reserves are depleted as cells are released into circulation for recruitment to infection sites. Expression of L-selectin on the cell membrane allows neutrophils to roll along the activated endothelium. Whereas mechanisms leading to recruitment to infection sites are well established, expression of BM adhesion molecules in cows is limited. In this study, we assessed L-selectin expression and chemotactic response to zymosan-activated serum (ZAS) in bovine BM cells and in circulating neutrophils. Isolated blood PMNL and BM cells were used from 9 dairy cows, for quantifying L-selectin expression using flow cytometry, and from 12 dairy cows for chemotaxis studies. All granulocytic maturation stages expressed L-selectin. The percentage of cells fluorescing increased significantly in BM band and mature granulocytes and reached maximal expression on circulating neutrophils. Bone marrow band and segmented cells showed the highest L-selectin density. Chemotaxis through micropore filters in response to zymosan-activated fetal bovine serum was first observed in the myelocytic and metamyelocytic stages, and it increased with maturation and release into the blood stream. From these results, we conclude that L-selectin expression varies among stages of granulocytic maturation within the BM and differs from circulating PMNL. Further, BM cells are capable of migration starting at the metamyelocytic stage, and compared with BM cells, circulating neutrophils are more chemotactively active.
Insights
Neutrophil L-selectin expression and migration increase with maturation. Circulating neutrophils exhibit greater chemotactic activity than bone marrow cells, aiding in inflammation response.
Area of Science:
- Veterinary immunology
- Cellular immunology
- Inflammation research
Background:
- Polymorphonuclear neutrophilic leukocytes (PMNL) are crucial in inflammation, migrating from bone marrow (BM) to infection sites.
- Neutrophil recruitment involves L-selectin-mediated rolling on activated endothelium, but bovine BM adhesion molecule expression is poorly understood.
- Understanding these mechanisms in cattle is vital for managing inflammatory diseases.
Purpose of the Study:
- To investigate L-selectin expression on bovine bone marrow cells and circulating neutrophils.
- To assess the chemotactic response of bovine bone marrow cells and neutrophils to zymosan-activated serum (ZAS).
- To elucidate the role of L-selectin and chemotaxis in neutrophil maturation and trafficking in dairy cows.
Main Methods:
- Flow cytometry was used to quantify L-selectin expression on isolated blood PMNL and BM cells from 9 dairy cows.
- Chemotaxis assays were performed using BM cells and circulating neutrophils from 12 dairy cows, with zymosan-activated fetal bovine serum as the chemoattractant.
- Granulocytic maturation stages were analyzed for L-selectin expression and migratory capacity.
Main Results:
- L-selectin was expressed across all granulocytic maturation stages, with highest density on bone marrow band and segmented cells.
- L-selectin expression significantly increased from BM band to mature granulocytes, reaching maximal levels on circulating neutrophils.
- Chemotaxis was observed from the myelocytic stage, increasing with maturation, and circulating neutrophils showed higher chemotactic activity than BM cells.
Conclusions:
- Bovine L-selectin expression and chemotactic potential vary significantly during granulocytic maturation and upon release into circulation.
- Bone marrow cells gain migratory capacity starting at the metamyelocytic stage.
- Circulating neutrophils are more chemotactically active than their bone marrow precursors, highlighting their readiness for inflammatory responses.
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