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Updated: Aug 8, 2026
Static Adhesion Assay for the Study of Integrin Activation in T Lymphocytes
Published on: June 13, 2014
The LFA-1 integrin supports rolling adhesions on ICAM-1 under physiological shear flow in a permissive cellular
A Sigal1, D A Bleijs, V Grabovsky
1Department of Immunology, The Weizmann Institute of Science, Rehovot, Israel.
Insights
Leukocyte function-associated antigen 1 (LFA-1) can mediate leukocyte rolling or firm adhesion on ICAM-1, depending on its avidity state. Low-avidity LFA-1 supports rolling under physiological shear, potentially stabilizing initial leukocyte adhesion.
Area of Science:
- Immunology
- Cellular Biology
- Biophysics
Background:
- Leukocyte adhesion to endothelial cells is critical for immune responses.
- The integrin LFA-1 and its ligand ICAM-1 are key mediators of leukocyte-endothelial cell interactions.
- Understanding LFA-1's adhesive functions under varying shear conditions is crucial for deciphering leukocyte trafficking.
Purpose of the Study:
- To investigate the distinct adhesive functions of LFA-1 (leukocyte function-associated antigen 1) on different cell types under varying shear flow conditions.
- To determine the role of LFA-1 avidity states and cytoskeletal interactions in mediating firm adhesion versus rolling interactions with ICAM-1.
- To elucidate the mechanisms by which LFA-1 contributes to leukocyte rolling and subsequent arrest on activated endothelium.
Main Methods:
- Utilized K562 cells and Jurkat cells expressing LFA-1 to study adhesion to immobilized ICAM-1 under subphysiological and physiological shear flow.
- Employed a beta2 cytoplasmic domain-deletion mutant of LFA-1 to assess the impact of avidity on adhesion dynamics.
- Analyzed LFA-1-mediated adhesion by examining cell rolling, firm adhesion, and adhesion strengthening under controlled shear stress.
Main Results:
- LFA-1 mediated firm arrest of Jurkat cells on ICAM-1 under subphysiological shear but induced rolling of K562 cells under physiological shear.
- LFA-1-mediated rolling on ICAM-1 was dependent on an intact I-domain, Mg2+ presence, and ICAM-1 density, and correlated with decreased avidity.
- A high-avidity LFA-1 mutant mediated firm arrest of K562 cells, suggesting cytoskeletal interactions modulate LFA-1 avidity and adhesive function.
Conclusions:
- LFA-1 can mediate both rolling and firm adhesion to ICAM-1, with the outcome dependent on the cell type and shear conditions.
- Low-avidity LFA-1 states, potentially regulated by cytoskeletal attachments, facilitate leukocyte rolling under physiological flow.
- This rolling function may stabilize initial leukocyte contact and allow for subsequent arrest upon encountering endothelial activation signals.
Abstract:
The LFA-1 integrin is crucial for the firm adhesion of circulating leukocytes to ICAM-1-expressing endothelial cells. In the present study, we demonstrate that LFA-1 can arrest unstimulated PBL subsets and lymphoblastoid Jurkat cells on immobilized ICAM-1 under subphysiological shear flow and mediate firm adhesion to ICAM-1 after short static contact. However, LFA-1 expressed in K562 cells failed to support firm adhesion to ICAM-1 but instead mediated K562 cell rolling on the endothelial ligand under physiological shear stress. LFA-1-mediated rolling required an intact LFA-1 I-domain, was enhanced by Mg2+, and was sharply dependent on ICAM-1 density. This is the first indication that LFA-1 can engage in rolling adhesions with ICAM-1 under physiological shear flow. The ability of LFA-1 to support rolling correlates with decreased avidity and impaired time-dependent adhesion strengthening. A beta2 cytoplasmic domain-deletion mutant of LFA-1, with high avidity to immobilized ICAM-1, mediated firm arrests of K562 cells interacting with ICAM-1 under shear flow. Our results suggest that restrictions in LFA-1 clustering mediated by cytoskeletal attachments may lock the integrin into low-avidity states in particular cellular environments. Although low-avidity LFA-1 states fail to undergo adhesion strengthening upon contact with ICAM-1 at stasis, these states are permissive for leukocyte rolling on ICAM-1 under physiological shear flow. Rolling mediated by low-avidity LFA-1 interactions with ICAM-1 may stabilize rolling initiated by specialized vascular rolling receptors and allow the leukocyte to arrest on vascular endothelium upon exposure to stimulatory endothelial signals.
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