Related Experiment Videos
Shear-dependent inhibition of granulocyte adhesion to cultured endothelium by dextran sulfate
1Pharmacia Experimental Medicine, La Jolla, CA 92037.
Abstract:
Adhesion of polymorphonuclear granulocytes (PMNs) in microvessels occurs in the presence of shear forces exerted by the blood flow. To model this in vitro, phorbol myristate acetate (PMA)-activated PMN were exposed to shear stress on cultured human umbilical vein endothelial cells (HUVECs) and on plastic dishes coated with bovine serum albumin (BSA). PMN adhesion to HUVECs averaged 36% of the total PMNs added and was reduced to 21% by shear stress of approximately 1.5 dynes.cm-2. On BSA, adhesion was reduced from 59% to 35%. Dextran sulfate (molecular weight 500,000) inhibited PMN adhesion in a dose-dependent manner when shear stress was applied. At a concentration of 1 mg.ml-1, inhibition was 72% on HUVECs and 76% on BSA. Half-maximal inhibition was reached at approximately 1 microgram.mL-1 dextran sulfate, corresponding to 2 nmol/L. Without shear stress, dextran sulfate had no effect on HUVECs and only a moderate effect on BSA. The murine monoclonal antibody (MoAb) 60.3, recognizing an epitope on the leukocyte adhesion glycoprotein CD18, inhibited PMN adhesion equally well with and without shear. A low dose of MoAb 60.3 enhanced the effect of dextran sulfate without shear stress. Flow cytometry (FACS) did not show inhibition of MoAb 60.3 binding to PMNs by dextran sulfate. These results indicate that a dextran sulfate-inhibitable adhesion process is important for PMN adhesion in the presence of shear stress.
Insights
Shear stress reduces polymorphonuclear granulocyte (PMN) adhesion to endothelial cells and albumin surfaces. Dextran sulfate significantly inhibits this adhesion under shear, highlighting a key mechanism in blood flow interactions.
Area of Science:
- Biomedical Engineering
- Cell Biology
- Immunology
Background:
- Polymorphonuclear granulocytes (PMNs) adhere to microvessels under blood flow shear forces.
- Understanding PMN adhesion mechanisms is crucial for inflammatory and immune responses.
Purpose of the Study:
- To investigate the role of shear stress in PMN adhesion to human umbilical vein endothelial cells (HUVECs) and bovine serum albumin (BSA) surfaces.
- To determine the inhibitory effects of dextran sulfate and a CD18-targeting monoclonal antibody (MoAb 60.3) on PMN adhesion under shear stress.
Main Methods:
- In vitro modeling of PMN adhesion using PMA-activated PMNs exposed to shear stress on HUVEC and BSA-coated surfaces.
- Dose-dependent inhibition assays using dextran sulfate and MoAb 60.3.
- Flow cytometry (FACS) to assess MoAb 60.3 binding to PMNs.
Main Results:
- Shear stress significantly reduced PMN adhesion to both HUVECs (36% to 21%) and BSA (59% to 35%).
- Dextran sulfate inhibited PMN adhesion in a dose-dependent manner under shear stress (up to 76% inhibition), with minimal effect without shear.
- MoAb 60.3 inhibited PMN adhesion equally with or without shear, and low doses enhanced dextran sulfate's effect without shear.
Conclusions:
- A dextran sulfate-inhibitable adhesion pathway is critical for PMN adhesion under shear stress.
- Shear stress modulates PMN adhesion mechanisms, distinct from those targeted by MoAb 60.3 alone.
- Dextran sulfate represents a potential therapeutic target for conditions involving PMN adhesion under flow.