title: LAG-3 expression defines a subset of CD4(+)CD25(high)Foxp3(+) regulatory T cells that are expanded at tumor sites.
abstract: Human natural regulatory CD4(+) T cells comprise 5-10% of peripheral CD4(+)T cells. They constitutively express the IL-2Ralpha-chain (CD25) and the nuclear transcription Foxp3. These cells are heterogeneous and contain discrete subsets with distinct phenotypes and functions. Studies in mice report that LAG-3 has a complex role in T cell homeostasis and is expressed in CD4(+)CD25(+) T regulatory cells. In this study, we explored the expression of LAG-3 in human CD4(+) T cells and found that LAG-3 identifies a discrete subset of CD4(+)CD25(high)Foxp3(+) T cells. This CD4(+)CD25(high)Foxp3(+)LAG-3(+) population is preferentially expanded in the PBMCs of patients with cancer, in lymphocytes of tumor-invaded lymph nodes and in lymphocytes infiltrating visceral metastasis. Ex vivo analysis showed that CD4(+)CD25(high)Foxp3(+)LAG-3(+) T cells are functionally active cells that release the immunosuppressive cytokines IL-10 and TGF-beta1, but not IL-2. An in vitro suppression assay using CD4(+)CD25(high)LAG-3(+) T cells sorted from in vitro expanded CD4(+)CD25(high) regulatory T cells showed that this subset of cells is endowed with potent suppressor activity that requires cell-to-cell contact. Our data show that LAG-3 defines an active CD4(+)CD25(high)Foxp3(+) regulatory T cell subset whose frequency is enhanced in the PBMCs of patients with cancer and is expanded at tumor sites.
authors.affiliation: Unit of Immunotherapy of Human Tumors, Fondazione Istituto Di Ricovero e Cura a Carattere Scientifico, Istituto Nazionale Tumori, Milan, Italy. chiara.castelli@istitutotumori.mi.it
authors.forename: Chiara
authors.initials: C
authors.lastname: Camisaschi
authors.forename: Chiara
authors.initials: C
authors.lastname: Casati
authors.forename: Francesca
authors.initials: F
authors.lastname: Rini
authors.forename: Michela
authors.initials: M
authors.lastname: Perego
authors.forename: Annamaria
authors.initials: A
authors.lastname: De Filippo
authors.forename: Frédéric
authors.initials: F
authors.lastname: Triebel
authors.forename: Giorgio
authors.initials: G
authors.lastname: Parmiani
authors.forename: Filiberto
authors.initials: F
authors.lastname: Belli
authors.forename: Licia
authors.initials: L
authors.lastname: Rivoltini
authors.forename: Chiara
authors.initials: C
authors.lastname: Castelli
mesh_terms: D015703:Antigens, CD / Q000096:biosynthesis / Q000276:immunology*; D002469:Cell Separation; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000096:biosynthesis / Q000276:immunology; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology*; D009369:Neoplasms / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D000093322:Lymphocyte Activation Gene 3 Protein
chemical_list: D015703:Antigens, CD; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D000093322:Lymphocyte Activation Gene 3 Protein; C000720326:Lag3 protein, human