A three-dimensional model system to study the interactions between human leukocytes and endothelial cells.

Area of Science:

• Immunology
• Cell Biology
• Biomedical Engineering

Background:

• Leukocyte adhesion and migration are crucial processes in inflammatory responses.
• Understanding these mechanisms is vital for developing targeted therapies.
• Existing models often lack the complexity to fully recapitulate in vivo conditions.

Purpose of the Study:

• To develop and validate a novel 3D model system for studying leukocyte-endothelial cell interactions.
• To investigate the differential adhesion and migration of monocytes and neutrophils.
• To elucidate the role of specific adhesion molecules, particularly the Leukocyte Cell Adhesion Molecule (LeuCAM) complex, under different stimuli.

Main Methods:

• Developed a 3D model using human endothelial cells on a collagen matrix.
• Implemented a new separation technique for simultaneous analysis of adhesion and transmigration.
• Utilized interleukin-1 (IL-1) and formyl-methionyl-leucyl-phenylalanine (fMLP) as stimuli.
• Employed monoclonal antibodies (mAbs) targeting leukocyte adhesion molecules (CD18, CD11a, CD11b, CD11c).

Main Results:

• Monocytes adhered more strongly than neutrophils to untreated endothelial cells.
• IL-1 significantly enhanced neutrophil adhesion and migration in a time-dependent manner.
• fMLP increased adhesion of both cell types but did not affect migration.
• LeuCAM (CD18) was critical for IL-1-mediated neutrophil migration, completely blocking it.
• Monocyte adhesion was only partially inhibited by anti-LeuCAM and anti-LFA-1 (CD11a) antibodies.

Conclusions:

• The novel 3D model system effectively allows simultaneous analysis of leukocyte adhesion and transmigration.
• The LeuCAM complex plays a differential and stimulus-dependent role in leukocyte-endothelial cell interactions.
• Targeting LeuCAM may be a promising strategy for modulating neutrophil-driven inflammation.