title: An immunologist's guide to CD31 function in T-cells.
abstract: Although it is expressed by all leukocytes, including T-, B-lymphocytes and dendritic cells, the immunoglobulin-like receptor CD31 is generally regarded by immunologists as a marker of endothelial cell lineage that lacks an established functional role in adaptive immunity. This perception has recently been challenged by studies that reveal a key role for this molecule in the regulation of T-cell homeostasis, effector function and trafficking. The complexity of the biological functions of CD31 results from the integration of its adhesive and signaling functions in both the immune and vascular systems. Signaling by means of CD31 is induced by homophilic engagement during the interactions of immune cells and is mediated by phosphatase recruitment or activation through immunoreceptor tyrosine inhibitory motifs (ITIMs) that are located in its cytoplasmic tail. Loss of CD31 function is associated with excessive immunoreactivity and susceptibility to cytotoxic killing. Here, we discuss recent findings that have brought to light a non-redundant, complex role for this molecule in the regulation of T-cell-mediated immune responses, with large impact on our understanding of immunity in health and disease.
authors.affiliation: William Harvey Research Institute, Barts' and The London School of Medicine, Queen Mary, University of London, Charterhouse Square, London EC1M 6BQ, UK. f.marelli-berg@qmul.ac.uk
authors.forename: Federica M
authors.initials: FM
authors.lastname: Marelli-Berg
authors.forename: Marc
authors.initials: M
authors.lastname: Clement
authors.forename: Claudio
authors.initials: C
authors.lastname: Mauro
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Caligiuri
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000235:genetics / Q000276:immunology; D002465:Cell Movement / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007111:Immunity, Cellular; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000235:genetics / Q000276:immunology*; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D019408:Platelet Endothelial Cell Adhesion Molecule-1
keywords: CD31; Cell signaling; MHC; PECAM-1; T-lymphocyte; Trafficking; tolerance