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Integrin activation by divalent ions affects neutrophil homotypic adhesion
C Spillmann1, D Osorio, R Waugh
1Department of Biochemistry and Biophysics, University of Rochester, Medical Center, Box 639, 601 Elmwood Ave., Rochester, NY 14642, USA.
Annals of Biomedical Engineering
|November 27, 2002
Summary
Increased beta 2 integrin affinity enhances leukocyte adhesion during cell collisions. This study used divalent cations to modulate integrin affinity, revealing its crucial role in the inflammatory response.
Area of Science:
- Immunology
- Cell Biology
- Biophysics
Background:
- Leukocyte activation of beta 2 integrins is vital for inflammation.
- Integrin affinity modulation is a key mechanism in leukocyte adhesion.
Purpose of the Study:
- To investigate the role of beta 2 integrin affinity changes in forming adhesive contacts.
- To understand how divalent cations influence neutrophil adhesion.
Main Methods:
- Micropipette technique used to bring neutrophils into contact.
- Divalent cations (Mg2+, Mn2+, Ca2+) employed to alter beta 2 integrin affinity.
- Adhesion frequency measured under various cation conditions and with soluble adhesion molecules.
Main Results:
- High affinity states (Mg2+, Mn2+) increased adhesion frequency (12-14%).
- Low affinity state (Ca2+) and absence of cations significantly reduced adhesion.
- ICAM-1 and anti-beta 2 integrin Fab fragments reduced adhesion, confirming beta 2 integrin's role.
Conclusions:
- Increased beta 2 integrin affinity promotes homotypic neutrophil adhesion during cell collisions.
- Adhesion mediated by high integrin affinity is relatively weak compared to cell arrest and migration scenarios.