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Updated: Apr 12, 2026

Static Adhesion Assay for the Study of Integrin Activation in T Lymphocytes
Published on: June 13, 2014
Different states of integrin LFA-1 aggregation are controlled through its association with tetraspanin CD9
Raquel Reyes1, Alicia Monjas2, María Yánez-Mó3
1Centro de Biología Molecular Severo Ochoa (CSIC-UAM), 28049 Madrid, Spain; Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Abstract:
The tetraspanin CD9 has been shown to interact with different members of the β1 and β3 subfamilies of integrins, regulating through these interactions cell adhesion, migration and signaling. Based on confocal microscopy co-localization and on co-immunoprecipitation results, we report here that CD9 associates with the β2 integrin LFA-1 in different types of leukocytes including T, B and monocytic cells. This association is resistant to stringent solubilization conditions which, together with data from chemical crosslinking, in situ Proximity Ligation Assays and pull-down experiments, suggest a primary/direct type of interaction mediated by the Large Extracellular Loop of the tetraspanin. CD9 exerts inhibitory effects on the adhesive function of LFA-1 and on LFA-1-dependent leukocyte cytotoxic activity. The mechanism responsible for this negative regulation exerted by CD9 on LFA-1 adhesion does not involve changes in the affinity state of this integrin but seems to be related to alterations in its state of aggregation.
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