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Departments of
*
Immunology and
Histopathology, Imperial College School of Medicine, Hammersmith Hospital, London, United Kingdom
The recruitment of Ag-specific T cells to sites of inflammation is
a crucial step in immune surveillance. Although the molecular
interactions controlling T cell extravasation are relatively well
characterized, the effects of these events on T cell function are still
poorly understood. Using an in vitro model of transendothelial
migration of human CD4+ memory T cells, we have
investigated the molecular and functional changes induced in T cells
that come into contact with the endothelium. First, we show that
transendothelial migration is precluded by signals that lead to T cell
division. In addition, activation of the transcription factor AP-1,
without induction of NF-
B, is observed in T cells after noncognate
interactions with endothelial cells (EC), a pattern of transcriptional
regulation different from that observed in dividing T cells.
Up-regulation of certain adhesion (CD11a, CD49d), activation (CD69),
and costimulatory (CD86) receptors accompany these transcriptional
events. Most importantly, recently migrated T cells display a faster
rate of migration when reseeded onto an EC monolayer. Finally, T cells
become hyperresponsive to antigenic challenge after noncognate
interactions with the endothelium. These effects appear not to be due
to the selection of preactivated T lymphocytes, because they occur also
in clonal T cell populations and appear to be mediated by
L
2 integrin-CD54 interactions. We
conclude that CD4+ memory T cell extravasation is
accompanied by phenotypic and functional changes induced by the
interactions with the EC, which favor tissue infiltration by T cells
and their further activation once they reach the antigenic
site.
This article has been cited by other articles:
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Z. Zhang, C. L. Gorman, A.-C. Vermi, C. Monaco, A. Foey, S. Owen, P. Amjadi, A. Vallance, C. McClinton, F. Marelli-Berg, et al. TCR{zeta}dimlymphocytes define populations of circulating effector cells that migrate to inflamed tissues Blood, May 15, 2007; 109(10): 4328 - 4335. [Abstract] [Full Text] [PDF] |
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G. Kassiotis and B. Stockinger Anatomical Heterogeneity of Memory CD4+ T Cells Due to Reversible Adaptation to the Microenvironment J. Immunol., December 15, 2004; 173(12): 7292 - 7298. [Abstract] [Full Text] [PDF] |
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