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Increased expression of leucocyte adherence-related glycoproteins by polymorphonuclear leucocytes during phagocytosis
C M Vandenbroucke-Grauls1, H M Thijssen, P A Tetteroo
1State University of Utrecht, Department of Clinical Microbiology, The Netherlands.
Abstract:
Phagocytosis of Staphylococcus aureus by human polymorphonuclear leucocytes (PMN) on the surface of endothelial cells is accompanied by adherence of the PMN to the endothelial surface and detachment of the endothelial cells from the culture monolayer. We studied the role of the leucocyte adherence-related glycoproteins (Leu-CAM: Mo1/LFA-1/150,95 or CD11a-c-CD18 complex) in these processes. Phagocytosis of S. aureus induced increased expression of the common beta chain (CD18) of Leu-CAM as demonstrated by flow cytometric analysis of PMN treated with a monoclonal antibody (MoAb) (CLB-LFA-1/1) directed against CD18 and fluorescein isothiocyanate (FITC)-conjugated anti-MoAb. This same MoAb also inhibited the increased adherence of the PMN to the endothelial cells which occurs during phagocytosis. Blocking of adherence during phagocytosis with MoAb CLT-LFA-1/1 had no effect on the detaching activity of the PMN on the endothelial cells. We conclude that adherence of PMN to endothelial cells during phagocytosis of S. aureus is mediated by the Leu-CAM complex. Adherence through the Leu-CAM, however, is not necessary for endothelial damage by the phagocytosing PMN.
Insights
Human white blood cells (PMN) use Leu-CAM glycoproteins to stick to endothelial cells during Staphylococcus aureus phagocytosis. This adherence is crucial, but not required for damaging endothelial cells.
Area of Science:
- Immunology
- Cell Biology
Background:
- Phagocytosis of Staphylococcus aureus by human polymorphonuclear leucocytes (PMN) involves PMN adherence to endothelial cells and endothelial cell detachment.
- The role of leucocyte adherence-related glycoproteins (Leu-CAM), specifically the CD11a-c-CD18 complex, in these processes requires investigation.
Purpose of the Study:
- To investigate the role of the Leu-CAM complex in PMN adherence to endothelial cells during S. aureus phagocytosis.
- To determine if Leu-CAM-mediated adherence is necessary for endothelial cell damage.
Main Methods:
- Flow cytometric analysis of PMN treated with a monoclonal antibody (MoAb) against CD18.
- Inhibition of PMN adherence using MoAb CLT-LFA-1/1 during phagocytosis.
- Assessment of endothelial cell detachment activity.
Main Results:
- Phagocytosis of S. aureus increased the expression of the CD18 component of Leu-CAM on PMN.
- The MoAb against CD18 inhibited PMN adherence to endothelial cells during phagocytosis.
- Blocking PMN adherence did not affect endothelial cell detachment.
Conclusions:
- PMN adherence to endothelial cells during S. aureus phagocytosis is mediated by the Leu-CAM complex.
- Leu-CAM-mediated adherence is not essential for the endothelial damage caused by phagocytosing PMN.