Active MAC-1 (CD11b/CD18) on DC is inhibitory for full T cell activation

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Item Type:	Article
Title:	Active MAC-1 (CD11b/CD18) on DC is inhibitory for full T cell activation
Creators Name:	Varga, G., Balkow, S., Wild, M.K., Stadtbaeumer, A., Krummen, M., Rothoeft, T., Higuchi, T., Beissert, S., Wethmar, K., Scharffetter-Kochanek, K., Vestweber, D. and Grabbe, S.
Abstract:	beta2 integrins are important for transendothelial migration of leukocytes as well as for T cell activation during antigen presentation. Despite abundant expression of beta2 integrins on APC, their functional relevance for antigen presentation is completely unclear. We show here that DC from CD18-deficient mice, which lack all functional beta2 integrins, have no defect in antigen presentation. Moreover, DC from normal mice express inactive beta2 integrins that do not become activated upon contact with T cells, at least in vitro. Pharmacological activation of beta2 integrins on DC results in a significant reduction of their T cell activating capacity. This effect is mediated by Mac-1 (CD11b/CD18) on DC since it could be reversed via blocking antibodies against CD18 and CD11b. Furthermore, the antigen presenting capacity of macrophages, that express constitutively active beta2 integrins, is significantly enhanced upon Mac-1 blockade. We therefore conclude that active CD11b/CD18 (Mac-1) on APC directly inhibits T cell activation.
Keywords:	Antigen Presentation, CD11b Antigens, CD18 Antigens, Cultured Cells, Dendritic Cells, Immunophenotyping, Lymphocyte Activation, Macrophage-1 Antigen, Macrophages, T-Lymphocytes, Animals, Mice
Source:	Blood
ISSN:	0006-4971
Publisher:	American Society of Hematology
Volume:	109
Number:	2
Page Range:	661-669
Date:	15 January 2007
Official Publication:	https://doi.org/10.1182/blood-2005-12-023044
PubMed:	View item in PubMed

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