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Updated: Jul 28, 2026
Real-time Imaging of Endothelial Cell-cell Junctions During Neutrophil Transmigration Under Physiological Flow
Published on: August 14, 2014
Antibodies to CD18 influence neutrophil migration through extracellular matrix
W M Saltzman1, T L Livingston, M R Parkhurst
1Department of Chemical Engineering, The Johns Hopkins University, Baltimore, Maryland, USA. saltzman@cheme.cornell.edu
Abstract:
Mac-1 (CD11b/CD18) is known to be involved in neutrophil (PMN) adhesion to endothelial cells and extracellular matrix. Although antibodies to CD 18 are being tested for therapy in humans, their role in PMN migration through the extracellular matrix is unknown. We used direct visualization to quantify PMN motility through reconstituted, three-dimensional gels of collagen type I. Gels were prepared with different concentrations of collagen (ranging from 0.1 to 1.0 mg/mL) and PMN migration was examined in the presence and absence of antibodies to CD18 (anti-CD18), with and without stimulation by N-formyl peptides. In low-concentration gels (<0.6 mg/mL), anti-CD18 had a significant influence on PMN migration, increasing motility in unstimulated PMN by 90% at 0.3 mg/mL collagen, and decreasing motility in N-formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated PMN by 70% at 0.4 mg/mL collagen. But antiCD18 had no effect on the rate of cell migration through high-concentration collagen gels (>0.6 mg/mL). PMN migration through collagen gels is CD18-dependent but only under conditions of high hydration, suggesting that CD18-mediated effects (e.g., adhesion to gel fibers) are only important when the fiber density is relatively low. Anti-CD18 inhibited, but did not eliminate, the adhesion of fMLP-stimulated PMN to the surface of collagen gels, suggesting that cells use multiple mechanisms for gaining traction within the gel. Because of the multiple modes of interaction between motile cells and the deformable fiber matrix, blockade of one component, such as CD18, can enhance the rate of cell migration under one set of conditions, and inhibit under another.
Insights
Antibodies targeting CD18 impact neutrophil migration through collagen gels, increasing movement in unstimulated cells and decreasing it in stimulated cells, depending on collagen concentration and hydration. This suggests CD18
Area of Science:
- Immunology
- Cell Biology
- Biophysics
Background:
- Mac-1 (CD11b/CD18) mediates neutrophil adhesion to endothelial cells and extracellular matrix.
- The role of CD18 antibodies in neutrophil migration through the extracellular matrix remains largely unknown.
- Neutrophil migration is crucial for inflammatory responses and tissue repair.
Purpose of the Study:
- To quantify the effect of CD18 antibodies on neutrophil (PMN) motility through three-dimensional collagen gels.
- To investigate how collagen concentration and N-formyl peptide stimulation influence CD18-mediated PMN migration.
- To elucidate the mechanisms by which CD18 antibodies affect PMN adhesion and migration within the extracellular matrix.
Main Methods:
- Direct visualization techniques were employed to track PMN migration in reconstituted collagen type I gels.
- Collagen gels were prepared at varying concentrations (0.1–1.0 mg/mL).
- PMN migration was assessed in the presence and absence of anti-CD18 antibodies, with and without fMLP stimulation.
Main Results:
- In low-concentration collagen gels (<0.6 mg/mL), anti-CD18 significantly increased unstimulated PMN motility by 90% and decreased fMLP-stimulated PMN motility by 70%.
- Anti-CD18 had no significant effect on PMN migration through high-concentration collagen gels (>0.6 mg/mL).
- Anti-CD18 partially inhibited the adhesion of fMLP-stimulated PMN to collagen gel surfaces, indicating multiple adhesion mechanisms.
Conclusions:
- Neutrophil migration through collagen gels is CD18-dependent, particularly under conditions of high hydration (low collagen concentration).
- CD18-mediated adhesion is critical for PMN migration when the extracellular matrix fiber density is low.
- Blocking CD18 can either enhance or inhibit neutrophil migration rates depending on the specific microenvironmental conditions and cell stimulation status.
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