title: Identification of novel immunoregulatory molecules in human thymic regulatory CD4+CD25+ T cells by phage display.
abstract: Thymic CD4+CD25+ cells play an important role in immune regulation and are continuously developed in the thymus as an independent lineage. How these cells are generated, what are their multiple pathways of suppressive activity and which are their specific markers are questions that remain unanswered. To identify molecules involved in the function and development of human CD4+CD25+ T regulatory cells we targeted thymic CD4+CD25+ cells by peptide phage display. A phage library containing random peptides was screened ex vivo for binding to human thymic CD4+CD25+ T cells. After four rounds of selection on CD4+CD25+ enriched populations of thymocytes, we sequenced several phage displayed peptides and selected one with identity to the Vitamin D Receptor (VDR). We confirmed the binding of the VDR phage to active Vitamin D in vitro, as well as the higher expression of VDR in CD4+CD25+ cells. We suggest that differential expression of VDR on natural Tregs may be related to the relevance of Vitamin D in function and ontogeny of these cells.
authors.affiliation: Heart Institute, Instituto do Coração, School of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Georgia
authors.initials: G
authors.lastname: Porto
authors.forename: Ricardo J
authors.initials: RJ
authors.lastname: Giordano
authors.forename: Luciana C
authors.initials: LC
authors.lastname: Marti
authors.forename: Beatriz
authors.initials: B
authors.lastname: Stolf
authors.forename: Renata
authors.initials: R
authors.lastname: Pasqualini
authors.forename: Wadih
authors.initials: W
authors.lastname: Arap
authors.forename: Jorge
authors.initials: J
authors.lastname: Kalil
authors.forename: Verônica
authors.initials: V
authors.lastname: Coelho
mesh_terms: D001435:Bacteriophages / Q000235:genetics*; D015704:CD4 Antigens / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000276:immunology; D006801:Humans; D053645:Interleukin-2 Receptor alpha Subunit / Q000276:immunology*; D018167:Receptors, Calcitriol / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology*
chemical_list: D015704:CD4 Antigens; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D053645:Interleukin-2 Receptor alpha Subunit; D018167:Receptors, Calcitriol