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Control of leukocyte integrin activation
1Macrophage Laboratory, Imperial Cancer Research Fund, London, United Kingdom.
The American Review of Respiratory Disease
|December 1, 1993
Summary
Leukocyte integrin activation, essential for cell adhesion, involves "inside out" signaling and conformational changes. Divalent cations like Mg2+ and Ca2+ influence this process, which is crucial for immune cell interactions.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Leukocyte integrins mediate cell-cell adhesion through specific ligand interactions.
- Integrin activation is a dynamic process involving "inside out" signaling pathways.
- The precise roles of divalent cations in integrin activation require further elucidation.
Purpose of the Study:
- To explore the mechanisms of leukocyte integrin activation.
- To understand the influence of divalent cations on integrin-ligand binding.
- To investigate conformational changes in integrins during activation and ligand binding.
Main Methods:
- Analysis of "inside out" signaling pathways.
- Investigating the effects of magnesium (Mg2+) and calcium (Ca2+) on integrin function.
- Utilizing anti-LFA-1 monoclonal antibodies (e.g., MEM-83) to probe integrin activation.
Main Results:
- Integrin activation is triggered by specific molecules, leading to high-affinity ligand pairing.
- Divalent cations, particularly Mg2+ and Ca2+, modulate integrin binding affinity.
- Anti-integrin antibodies can mimic activation, indicating conformational changes.
- Ligand binding induces novel epitopes termed "ligand-induced binding sites".
Conclusions:
- Leukocyte integrin activation is transient, enabling short-lived cell-cell adhesion.
- This transient adhesion is vital for the dynamic interactions and recycling of immune effector cells.
- Understanding integrin cation-dependency is key to deciphering immune cell trafficking and function.