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Updated: Aug 21, 2026

Static Adhesion Assay for the Study of Integrin Activation in T Lymphocytes
Published on: June 13, 2014
The functional interaction of the beta 2 integrin lymphocyte function-associated antigen-1 with junctional adhesion
Line Fraemohs1, Rory R Koenen, Georg Ostermann
1Department of Molecular Cardiovascular Research, Rheinisch-Westfälische Technische Hochschule, University Hospital Aachen, Pauwelsstrasse 30, 52074 Aachen, Germany.
Abstract:
Binding of the beta(2) integrin LFA-1 (alpha(L)beta(2)) to junctional adhesion molecule-A (JAM-A) has been shown to enhance leukocyte adhesion and transendothelial migration. This is mediated by the membrane-proximal Ig-like domain 2 of JAM-A; however, the location of the JAM-A binding site in LFA-1 has not been identified. We have deleted the I domain in the alpha(L) subunit of LFA-1 and expressed this alpha(L) mutant in alpha(l)-deficient Jurkat J-beta(2).7 cells to demonstrate that the I domain of LFA-1 is crucial for their adhesion to immobilized JAM-A. This was substantiated by blocking the stimulated adhesion of wild-type Jurkat T cells or monocytic Mono Mac 6 cells to JAM-A using the I domain-directed mAb TS1/22 or the small molecule antagonist BIRT 377, which stabilizes the low-affinity conformation of the I domain. The immobilized LFA-1 I domain locked in the open high-affinity conformation was sufficient to support binding of transfected Chinese hamster ovary cells expressing JAM-A. Solid-phase binding assays confirmed a direct interaction of recombinant JAM-A with the immobilized locked-open I domain. These data provide the first evidence that the I domain of LFA-1 contains a functional binding site for JAM-A.
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