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Effect of divalent cations on adhesion of polymorphonuclear leukocytes to matrix molecules in vitro
E Lundgren-Akerlund1, E Berger, K E Arfors
1La Jolla Institute for Experimental Medicine, California.
Abstract:
Adhesion of N-formyl-methionyl-leucylphenylalanine-stimulated human polymorphonuclear leukocytes (PMNs) to dishes coated with laminin, fibronectin, or collagen types I and IV was dependent on the presence of magnesium (Mg2+) but not calcium (Ca2+). Addition of manganese (Mn2+) in combination with Ca2+ and Mg2+ further increased the number of PMNs adhering to the matrix proteins. Monoclonal antibody 60.3 (mAb 60.3) was equally effective at inhibiting adhesion of PMNs to all the matrix proteins. The presence of Mn2+ (50 microM), in addition to 1 mM Ca2+ and Mg2+, required higher concentrations of mAb 60.3 to inhibit adhesion of PMNs to collagens type I or IV, suggesting increased affinity of PMNs for these substrates. These findings suggest that the PMNs may regulate the affinity of CD11/CD18 for multiple ligands by binding different divalent cations to the receptor.
Insights
Magnesium is crucial for human polymorphonuclear leukocytes (PMNs) adhesion to matrix proteins. Divalent cations like manganese can enhance PMN binding, suggesting a role in regulating receptor affinity.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Human polymorphonuclear leukocytes (PMNs) play a critical role in immune responses.
- Leukocyte adhesion to extracellular matrix proteins is essential for migration and function.
- The role of divalent cations in modulating PMN adhesion to specific matrix proteins requires further elucidation.
Purpose of the Study:
- To investigate the role of divalent cations (Mg2+, Ca2+, Mn2+) in PMN adhesion to laminin, fibronectin, and collagen types I and IV.
- To determine the effect of manganese in combination with other cations on PMN adhesion.
- To assess the involvement of the CD11/CD18 receptor in cation-dependent PMN adhesion.
Main Methods:
- PMN adhesion assays using substrates coated with laminin, fibronectin, and collagen.
- Stimulation of PMNs with N-formyl-methionyl-leucylphenylalanine.
- Addition of various divalent cations (Mg2+, Ca2+, Mn2+) to adhesion assays.
- Inhibition studies using monoclonal antibody 60.3 (mAb 60.3).
Main Results:
- PMN adhesion to matrix proteins was dependent on Mg2+ but not Ca2+.
- Mn2+ significantly enhanced PMN adhesion when combined with Ca2+ and Mg2+.
- Higher concentrations of mAb 60.3 were needed to inhibit adhesion to collagen when Mn2+ was present, indicating increased PMN affinity.
Conclusions:
- Divalent cations, particularly Mg2+ and Mn2+, play a significant role in regulating PMN adhesion to extracellular matrix proteins.
- The CD11/CD18 receptor's affinity for multiple ligands can be modulated by the binding of different divalent cations.
- These findings provide insights into the mechanisms governing leukocyte migration and immune cell interactions with the extracellular matrix.