Although ICAM-3 is implicated in both adhesion and signal transduction events of leukocytes, its low affinity for LFA-1 compared to other ligands of LFA-1 has puzzled many investigators. Here we investigated the role of ICAM-3 in supporting LFA-1-mediated ICAM-1 binding and subsequently cell signaling. We observed that although ICAM-3 binds poorly to LFA-1 expressed on resting T cells, it specifically facilitates and increases LFA-1-mediated adhesion to the high affinity ligand of LFA-1, ICAM-1. We demonstrate that low-affinity binding of LFA-1 to ICAM-3 together with ICAM-1 alters the cell surface distribution of LFA-1 dramatically, inducing large clusters of LFA-1 that facilitate ICAM-1 binding after LFA-1 activation. We found that LFA-1-mediated ICAM-1 cell-cell interactions such as T cell proliferation greatly depend on low affinity LFA-1/ICAM-3 interactions that enhance stable LFA-1/ICAM-1 cell-cell contact. Taken together, these data demonstrate that low affinity LFA-1 binding to ICAM-3 regulates strong LFA-1/ICAM-1-mediated adhesion by driving LFA-1 into clusters to facilitate cell-cell interactions that take place in the immune system.
Low-affinity LFA-1/ICAM-3 interactions augment LFA-1/ICAM-1-mediated T cell adhesion and signaling by redistribution of LFA-1
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D.A. Bleijs, M.E. Binnerts, S.J. van Vliet, C.G. Figdor, Y. van Kooyk; Low-affinity LFA-1/ICAM-3 interactions augment LFA-1/ICAM-1-mediated T cell adhesion and signaling by redistribution of LFA-1. J Cell Sci 1 February 2000; 113 (3): 391–400. doi: https://doi.org/10.1242/jcs.113.3.391
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